And in case you were wondering, the cost of housing a prisoner in jail on NYC's Rikers Island is now officially $100,000 per year! You get what you pay for, they say. $1.1 billion dollars. 42 percent higher than seven years ago. "During the same period, there was a 124 percent increase in assaults on the staff by inmates at city jails, and triple the number of allegations of use of physical force by guards." Mazel Tov.