US population is 300+ million.
One out of ten would be 30+ million.
U.S. Sees First Decrease in Prison Population in Nearly 40 Years
WASHINGTON, D.C. The U.S. prison population has dropped for the first time in nearly 40 years.
According to the most recent government data, the number of inmates is down 1.3 percent, to about 7 million offenders behind bars...
Thought you might quote a different statistic. Sometime in the last few years, either the WaPo or NYT had an article pondering the deep mystery of why, with crime rates dropping, we still kept large numbers of people in prison. They simply could see no connection between large numbers of criminals locked away and the streets becoming safer.
A large number of people in prison is not in itself a bad thing. The best cure for recidivism is capital punishment, but long prison terms at least delay it.