According to the Federal Bureau of Prisons, 46.2% of inmates are in for drug offenses[1] and there is definitely disagreement about whether that should be a crime, let alone an extreme crime. Additionally, 78.6% of inmates are serving sentences longer than 5 years[2], which by necessity means that a large portion of those are for drug offenses.
[1] https://www.bop.gov/about/statistics/statistics_inmate_offen... [2] https://www.bop.gov/about/statistics/statistics_inmate_sente...