How is the "Cache static content" score determined?

I’ve run webpagetest on two different sites but got some strange results for the section “Leverage browser caching of static assets”. The first page had a lower score than the second, but the second had many more items listed.

First page: 67/100

FAILED - (No max-age or expires) - http://pokemondb.net/pokedex/game/black-white FAILED - (No max-age or expires) - https://googleads.g.doubleclick.net/pagead/drt/si?p=CAA&ut=AFAKxlQAAAAAUhx0xZDs_2A1-oPNp5s5tq0SfRhWy01o FAILED - (No max-age or expires) - https://googleads.g.doubleclick.net/pagead/drt/si?p=CAA&ut=AFAKxlQAAAAAUhx0xZDs_2A1-oPNp5s5tq0SfRhWy01o FAILED - (No max-age or expires) - http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-4942990752504243&format=728x90&output=html&h=90&slotname=5568695004&w=728&lmt=1377595713&flash=11.8.800.94&url=http%3A%2F%2Fpokemondb.net%2Fpokedex%2Fgame%2Fblack-white&dt=1377595712356&bpp=34&bdt=255&shv=r20130820&cbv=r20130206&saldr=aa&correlator=1377595712795&frm=20&adk=2524201259&ga_vid=1960857529.1377595713&ga_sid=1377595713&ga_hid=224680574&ga_fc=1&u_tz=-240&u_his=0&u_java=1&u_h=1200&u_w=1920&u_ah=1160&u_aw=1920&u_cd=24&u_nplug=0&u_nmime=0&dff=times%20new%20roman&dfs=13&adx=129&ady=479&biw=991&bih=698&oid=3&docm=9&vis=0&fu=0&ifi=1&dtd=708&xpc=DME76fJ1MI&p=http%3A//pokemondb.net FAILED - (No max-age or expires) - http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-4942990752504243&format=728x90&output=html&h=90&slotname=9080564600&w=728&lmt=1377595713&flash=11.8.800.94&url=http%3A%2F%2Fpokemondb.net%2Fpokedex%2Fgame%2Fblack-white&dt=1377595712356&bpp=134&bdt=255&shv=r20130820&cbv=r20130206&saldr=aa&prev_fmts=728x90&correlator=1377595712795&frm=20&adk=2642709296&ga_vid=1960857529.1377595713&ga_sid=1377595713&ga_hid=224680574&ga_fc=1&u_tz=-240&u_his=0&u_java=1&u_h=1200&u_w=1920&u_ah=1160&u_aw=1920&u_cd=24&u_nplug=0&u_nmime=0&dff=times%20new%20roman&dfs=13&adx=129&ady=5211&biw=991&bih=698&oid=3&docm=9&vis=0&fu=0&ifi=2&dtd=827&xpc=Gx5RuPNUn2&p=http%3A//pokemondb.net FAILED - (26.1 minutes) - http://googleads.g.doubleclick.net/pagead/drt/s?v=r20120211 WARNING - (60.0 minutes) - http://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js WARNING - (60.0 minutes) - http://pagead2.googlesyndication.com/pagead/osd.js WARNING - (8.0 hours) - https://s2.googleusercontent.com/s2/favicons?domain_url=www.nanoseedz.com WARNING - (12.0 hours) - http://www.google-analytics.com/ga.js WARNING - (24.0 hours) - http://pagead2.googlesyndication.com/pagead/images/adchoices/en-000000.png WARNING - (24.0 hours) - http://pagead2.googlesyndication.com/pagead/expansion_embed.js WARNING - (24.0 hours) - https://s2.googleusercontent.com/s2/favicons?domain_url=yellowpages.com

Second page: 91/100

FAILED - (No max-age or expires) - http://fw.adsafeprotected.com/dt?asId=a3adb521-0efa-11e3-b1a6-0025904ea172&tv={c:msHXAw,pingTime:-2,time:84,type:a,fc:0,rt:0,cb:0,np:1,em:true,fr:false,slTimes:{i:0,o:0,n:84,pp:0,pm:0,gpp:0,gpm:0,gi:0,go:0,gn:84,fi:0,fo:0,fn:84},slEvents:[{sl:n,fsl:fn,gsl:gn,t:64,ac:140.13264.728.90,am:i,cc:0.0.728.0,piv:-1}],slEventCount:1,uf:1,e:D,tt:jss,fm:+1111|1112|1211,sinceFw:79,readyFired:true}&br=i&adsafePrivacyPolicy=http://integr.al/privacy-policy FAILED - (No max-age or expires) - https://googleads.g.doubleclick.net/pagead/drt/si?p=CAA&ut=AFAKxlQAAAAAUhx0GC82M3n1xhbaBeFP4jxaauaXiu4f FAILED - (No max-age or expires) - http://ad.doubleclick.net/adj/N7443.668587.AODDISPLAY/B7762931.28;sz=728x90;ord=2308435617242568216?;click=http://r.turn.com/r/tpclick/id/GFaamPY1CSAvJQwA8wUBAA/3c/http%3A%2F%2Fadclick.g.doubleclick.net%2Faclk%3Fsa%3DL%26ai%3DClTPCk3AcUuW6C6rb0AGhzYHQDo7zqp4Cnt3h5Cq-g86hcxABIABQgMfhxARgyYaAgOwkggEXY2EtcHViLTQ4MDc0NTc5NTczOTI1MDjIAQmoAwGqBI8BT9AjdNnwsyPCE4O0SvO_9xPgXST4aQ3dY5kEHbv6h3bMTIiO6LnJ_jhYUyxDcmIlXFZFT5tP_sHZ0qDxFCSeg7Ud3I9JOgsPb8maE-KYc9JztitauSgkcdOPmWim7TZw6nKort0xL1wgp2Nqv7fKfBD5BKHCP1ddSGUiejSK305wMKK1hiqiTlG_XYir2qCABuCilt3m3M3tFKAGIQ%26num%3D1%26sig%3DAOD64_0mThY3rC1WtZhkadhkXymTKJG8dQ%26client%3Dca-pub-4807457957392508%26adurl%3D/url/; FAILED - (No max-age or expires) - http://fw.adsafeprotected.com/dt?asId=a3adb521-0efa-11e3-b1a6-0025904ea172&tv={c:msHXAw,pingTime:-3,time:644,type:v,fc:0,rt:0,cb:0,np:1,em:true,fr:false,slTimes:{i:644,o:0,n:644,pp:0,pm:0,gpp:0,gpm:0,gi:0,go:0,gn:644,fi:0,fo:0,fn:644},slEvents:[{sl:n,fsl:fn,gsl:gn,t:64,ac:140.13264.728.90,am:i,cc:0.0.728.0,piv:-1},{sl:i,fsl:fi,gsl:gn,t:644,ac:140.14864.728.90,am:i,cc:0.0.728.0,piv:100}],slEventCount:2,uf:1,e:D,tt:jss,fm:+1111|1112|1211}&br=i&adsafePrivacyPolicy=http://integr.al/privacy-policy FAILED - (No max-age or expires) - http://fw.adsafeprotected.com/dt?asId=a3adb521-0efa-11e3-b1a6-0025904ea172&tv={c:msHXAw,pingTime:1,time:1204,type:p,fc:0,rt:0,cb:0,np:1,em:true,fr:false,slTimes:{i:1204,o:0,n:644,pp:0,pm:0,gpp:0,gpm:0,gi:0,go:0,gn:1204,fi:560,fo:0,fn:644},slEvents:[{sl:n,fsl:fn,gsl:gn,t:64,ac:140.13264.728.90,am:i,cc:0.0.728.0,piv:-1},{sl:i,fsl:fi,gsl:gn,t:644,ac:140.14864.728.90,am:i,cc:0.0.728.0,piv:100}],slEventCount:2,uf:1,e:D,tt:jss,fm:+1111|1112|1211}&br=i&adsafePrivacyPolicy=http://integr.al/privacy-policy FAILED - (No max-age or expires) - http://www.serebii.net/blackwhite/pokemon.shtml FAILED - (No max-age or expires) - http://googleads.g.doubleclick.net/pagead/adview?ai=ClTPCk3AcUuW6C6rb0AGhzYHQDo7zqp4Cnt3h5Cq-g86hcxABIABQgMfhxARgyYaAgOwkggEXY2EtcHViLTQ4MDc0NTc5NTczOTI1MDjIAQmoAwGqBI8BT9AjdNnwsyPCE4O0SvO_9xPgXST4aQ3dY5kEHbv6h3bMTIiO6LnJ_jhYUyxDcmIlXFZFT5tP_sHZ0qDxFCSeg7Ud3I9JOgsPb8maE-KYc9JztitauSgkcdOPmWim7TZw6nKort0xL1wgp2Nqv7fKfBD5BKHCP1ddSGUiejSK305wMKK1hiqiTlG_XYir2qCABuCilt3m3M3tFKAGIQ&sigh=97rIeVqkyGo FAILED - (No max-age or expires) - http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-4807457957392508&output=html&h=90&slotname=7960574568&w=728&lmt=1377595535&ea=0&flash=11.8.800.94&url=http%3A%2F%2Fwww.serebii.net%2Fblackwhite%2Fpokemon.shtml&dt=1377595535290&bpp=3&bdt=317&shv=r20130820&cbv=r20130206&saldr=sa&prev_fmts=468x60_as&correlator=1377595535446&frm=20&adk=3758836677&ga_vid=393293509.1377595535&ga_sid=1377595535&ga_hid=1112163535&ga_fc=0&u_tz=-240&u_his=0&u_java=1&u_h=1200&u_w=1920&u_ah=1160&u_aw=1920&u_cd=32&u_nplug=0&u_nmime=0&dff=times%20new%20roman&dfs=16&adx=130&ady=8900&biw=987&bih=694&oid=3&docm=8&vis=0&fu=0&ifi=2&dtd=293 FAILED - (No max-age or expires) - http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-4807457957392508&format=468x60_as&output=html&h=60&w=468&lmt=1377595535&channel=0862402736&ad_type=text&ea=0&color_bg=2F9840&color_border=4F7830&color_link=000000&color_text=000000&color_url=008000&flash=11.8.800.94&url=http%3A%2F%2Fwww.serebii.net%2Fblackwhite%2Fpokemon.shtml&dt=1377595535185&bpp=9&bdt=212&shv=r20130820&cbv=r20130206&saldr=sa&correlator=1377595535446&frm=20&adk=1920154430&ga_vid=393293509.1377595535&ga_sid=1377595535&ga_hid=1112163535&ga_fc=0&u_tz=-240&u_his=0&u_java=1&u_h=1200&u_w=1920&u_ah=1160&u_aw=1920&u_cd=32&u_nplug=0&u_nmime=0&dff=verdana&dfs=0&adx=260&ady=161&biw=987&bih=694&oid=3&docm=8&vis=0&fu=0&ifi=1&dtd=291 FAILED - (10.0 minutes) - http://c.betrad.com/a/n/273/9582.js FAILED - (29.0 minutes) - http://googleads.g.doubleclick.net/pagead/drt/s?v=r20120211 WARNING - (60.0 minutes) - http://pagead2.googlesyndication.com/pagead/show_ads.js WARNING - (60.0 minutes) - http://c.betrad.com/geo/ba.js?1159 WARNING - (60.0 minutes) - http://c.betrad.com/a/4.gif WARNING - (60.0 minutes) - http://c.betrad.com/icon/box_19_top-right.png WARNING - (60.0 minutes) - http://c.betrad.com/surly.js?;ad_w=728;ad_h=90;coid=273;nid=9582;crid=667; WARNING - (60.0 minutes) - http://pagead2.googlesyndication.com/pagead/osd.js WARNING - (60.0 minutes) - http://c.betrad.com/icon/ci.png WARNING - (24.0 hours) - http://pagead2.googlesyndication.com/pagead/images/mobile_unified_button_icon_white.png WARNING - (24.0 hours) - http://pagead2.googlesyndication.com/pagead/images/adchoices/en-ffffff.png WARNING - (24.0 hours) - http://s0.2mdn.net/3756078/2-Sprint_Business_SDC_BOG4_728x90.jpg WARNING - (24.0 hours) - https://s2.googleusercontent.com/s2/favicons?domain_url=www.restorationcontract.com/ WARNING - (24.0 hours) - http://pagead2.googlesyndication.com/pagead/js/graphics.js WARNING - (2.0 days) - http://www.google.com/cse/intl/en/images/google_custom_search_watermark.gif WARNING - (2.0 days) - http://ad.turn.com/server/ads.js?pub=31458155&cch=31458192&code=31458489&l=728x90&aid=32202281&ahcid=7879241&bimpd=zvptdH46qDrSRN9Ei3CJF8xjTJGBtoYfBqUEpCbJTqnI_e8fZd8MZoA2T98WKPxyiq8Ti8UkXoHM4mFYS4pi8i98lk7F1SjlSY5NgrrOC1dYNV2lBMSlRE5s1NOD3liyNTv5hCkJ7H66ela5Au6VRH1eQ4IQLhiT-mFWW8dGpGuB4sOONpGxwZnpxhs1fIyfOWB4hVe5s5HKpKQCgjxtf0r6E4DPTQ5gZ-dd8i6p23d-iJOFRxJ6kJxJWBMY726NnGbBibXMMIuD46r6l_e4EZYV7DkDNWxuUD4L_eSABu6JmgZ7Zwrzz0qF48Jt_WD9JTYWHzblIH4UaXJJ3ZimiIDDUwzPyaEC7iuJzkAFnslxEUl22trjrVzSuF6Y2pdEMziqN4hBTdnNd14sahsq9AD5aQVJrEhkh1saYKvFE58w3iq-H9mNdQPKh2CjTUIbQp420Cz5mXiKFF_3z-r1sfZ4yan-Bk9ByhW6kKVie3imx6zkp41i9h_mYTYCQVD1oxU1fgJLCGBw-sDQqC89TDpu_0s2nJJ2Ls9NMkSfPhmKyZHWarBIM2wGCEDvawmgGDZTZ1Ld20LQ3Nxxzv60mr3wc-cQ7FRKnITKYzO3zYVes-piZCwjI7F8AxYRWg3khT3mS5xHAjYgNWElbau4tYAh_xpxclTbqHgpajaD5YfRMNsWzcSR052BNUEweMQ_KdWoOL0PTpETvGb90a-ZFL3wc-cQ7FRKnITKYzO3zYX4x9DeUo2rqrArx3jiHAYPT9uA8AxqkXdaZm0Mo6blSBtZnmMk_yG5lbaNSrfC7W5iiZTRPlDtNbnOTVydZzeRffe92CUejuhUFkTilT8P0Zksv-ufm9VM8NnDmCN5qUzUyzzD-ofOoF9Zvh4yyWYbl0C5IpVBbS2AFLzUh-lXkZmFVFD9Wc-zNTa6k-V6oeft_T370WDWWY1SqEwEJwbh-dHiCifwjBHGabrqHhKf-n1kLB974_R8r_Y3L_M75tUSSS8thMwlQuwywEvz9oZzM2HJt0tqBTcuCmAEugTCKkFvM7hkNYEwZ4rbptjF422wTeBDmVMNlmOrhnXrV9uV0pQ2byriMis5d97R5dWOpa5GmNcVzGU-LnnjmZD3aXPqqTKaMqti6P3gXlTdi2wa&acp=UhxwkwAC3WUKNC2qAABmoR1zDa4w_z-mOLtUzw&3c=http://adclick.g.doubleclick.net/aclk%3Fsa%3DL%26ai%3DClTPCk3AcUuW6C6rb0AGhzYHQDo7zqp4Cnt3h5Cq-g86hcxABIABQgMfhxARgyYaAgOwkggEXY2EtcHViLTQ4MDc0NTc5NTczOTI1MDjIAQmoAwGqBI8BT9AjdNnwsyPCE4O0SvO_9xPgXST4aQ3dY5kEHbv6h3bMTIiO6LnJ_jhYUyxDcmIlXFZFT5tP_sHZ0qDxFCSeg7Ud3I9JOgsPb8maE-KYc9JztitauSgkcdOPmWim7TZw6nKort0xL1wgp2Nqv7fKfBD5BKHCP1ddSGUiejSK305wMKK1hiqiTlG_XYir2qCABuCilt3m3M3tFKAGIQ%26num%3D1%26sig%3DAOD64_0mThY3rC1WtZhkadhkXymTKJG8dQ%26client%3Dca-pub-4807457957392508%26adurl%3D WARNING - (2.0 days) - http://www.google.com/coop/cse/brand?form=searchbox_018410473690156091934%3A6gahkiyodbi

It’s based on the percent of resources that are cached out of the total count of static resources, not the absolute counts.