Timeline USA. Prison, jail, probation, parole View source History Talk0 1,498pages on this wiki Template page USA: Over 7.2 million persons on probation or parole, or incarcerated in jail or prison, at yearend 2006. About 3.2% of the U.S. adult population, or 1 in every 31 adults. Larger chart with detailed source info: [1]. Latest data: [2]. See template.Added by Timeshifter Related Categories Categories: Chart and graph templatesDrug-war-related statistics