"The number of juvenile inmates confined in local jails decreased 62% between 2008 (7,700 inmates) and 2019 (2,900 inmates). About 3 in 4 juveniles in jail (76%) were held as adults in 2019."
Source
Zhen Zeng, PhD, and Todd D. Minton. Jail Inmates In 2019. Washington, DC: US Department of Justice Bureau of Justice Statistics. March 2021. NCJ255608.