These stats are taken from my 2007 W-2:

Tax  % of AGI
Days of year Date
Federal Income 20.2739 74.048838 01:10:20 GMT, Fri, March 16th 2007
State Income 6.0718 22.176775 05:24:53 GMT, Sat, April 7th 2007
Social Security 5.7599 21.037585 06:19:00 GMT, Sat, April 28th 2007
Medicare 1.6571 6.052428 07:35:02 GMT, Fri, May 4th 2007

Total percentage of AGI: 33.7628%

Total days spent explicitly for the government: 123.315993

This obviously doesn’t include the matching Social Security funds my employer pays, property taxes I pay indirectly through my landlord, NJ sales tax, state and federal gas taxes, import and export taxes, corporate income taxes, etc.