https://www.bop.gov/about/statistics/statistics_inmate_offenses.jsp
About 46% are incarcerated for crimes related to drugs, which of course can lead to violence.
a Banking and Insurance, Counterfeit, Embezzlement 475 0.3%
b Burglary, Larceny, Property Offenses 8,113 4.7%
c Continuing Criminal Enterprise 376 0.2%
d Courts or Corrections 788 0.5%
e Drug Offenses 79,190 46.2%
f Extortion, Fraud, Bribery 10,961 6.4%
g Homicide, Aggravated Assault, and Kidnapping Offenses 5,559 3.2%
h Immigration 12,115 7.1%
i Miscellaneous 1,275 0.7%
j National Security 66 0.0%
k Robbery 6,320 3.7%
l Sex Offenses 16,154 9.4%
However, drug crimes is an umbrella that many fit under. Possession and use are a sickness imo, compared to possession with intent to sell.
I don't go with legalizing drugs to eliminate the crime, but I do think that drug use is a symptom... it might indicate a childhood of abuse or a person who is trans gender or gay that can't deal with it. Not to mention those who are hooked on opioids after a medical procedure and then turn to street drugs when they can't get a prescription any longer.
And we need to look at the fact that many of the prisons are ran privately and are a for profit enterprise.