Overrun with prisoners

The U.S. Department of Justice released new statistics on the U.S. prison population today, so I thought I go look at how our prison population compares with that of other countries. Here's what I found:

The United States has the highest prison population rate in the world, some 701 per 100,000 of the national population, followed by Russia (606), Belarus (554), Kazakhstan and the U.S. Virgin Islands (both 522), the Cayman Islands (501), Turkmenistan (489), Belize (459), Bermuda (447), Suriname (437), Dominica (420) and Ukraine (415). However, more than three fifths of countries (60.5%) have rates below 150 per 100,000. (The United Kingdom’s rate of 141 per 100,000 of the national population places it above the midpoint in the World List; it is the highest among countries of the European Union.)

Some great company we have up there at the top of the list, Turkmenistan, Kazakhstan, etc. Is this a sign that we have a truly sick society or is there some more benign explanation? I really don't know.