If pro-drug libertarians are posting it, it's very likely intended to deliberately mislead.
I didn't just claim it, I proved it. The DEA says, "In 1880 [...] there were over 400,000 opium addicts in the U.S. [...] By 1900, about one American in 200 was either a cocaine or opium addict." (http://web.archive.org/web/20110529221013/http://www.justice.gov/dea/demand/speakout/06so.htm) 400,000 in a population of 50M is one in 125 - ergo, between 1880 and 1900 addiction declined. Nonetheless, in textbook Drug Warrior fashion, they claim, " Addiction skyrocketed." Hilarious!