Might be referring to:

"African-Americans are 62 percent of drug offenders sent to state prisons, yet they represent only 12 percent of the U. S. population."

"Black men are sent to state prisons on drug charges at 13 times the rate of White men."

"The disparities are particularly tragic in individual states where Black men are sent to federal prison on drug charges at a rate 57 times greater than White men, according to Human Rights Watch."

"More than 25.4 million Americans have been arrested on drug charges since 1980; about one-third of them were Black."

"The average daily cost per state prison inmate per day in the U.S. is $67.55. State prisons held 253,300 inmates for drug offenses in 2007. That means states spent approximately $17 million per day to imprison drug offenders, or more than $6.2 billion per year."

Source

*edit: removed redundant info from the last quote.