128k out of 1.6m, or 8%. Graph of the incarcerated population: http://en.wikipedia.org/wiki/File:US_incarceration_timeline-.... The prison population started exploding in 1980 with the drug war and the war on immigration, but for-profit prisons had less than 10,000 prisoners as of 1990. It's a lagging effect--the for-profit prisons are sprouting up because we put so many people in prison, not the other way around.