what is an extraction rate
This term has several definitions.
http://www.google.com/#hl=en&sugexp=llsfp&pq=president%20truman&xhr=t&q=extraction+rate&cp=15&pf=p&sclient=psy&aq=0&aqi=&aql=&oq=extraction+rate&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=a445e974b90b3339