The United States, which has the most prisoners of any country in the world, last year recorded the largest increase in the number of people in prisons and jails since 2000, the Justice Department reported on Wednesday. It said the nation's prison and jail populations increased by more than 62,000 inmates, or 2.8 percent, to about 2,245,000 inmates in the 12-month period that ended on June 30, 2006. It was the biggest jump in numbers and percentage change in six years. Criminal justice experts have attributed the record U.S. prison population to tough sentencing laws, record numbers of drug offenders and high crimes rates, the Associated Press reported.