In 2012, 4,309 inmates died while in the custody of local jails or state prisons [in the US]. (...) The number of deaths in local jails increased, from 889 in 2011 to 958 in
2012 (...) More than a third (36%) of deaths in local jails occurred within 7 days of admission
https://www.bjs.gov/content/pub/pdf/mljsp0012st.pdf