Another part that effects the current prison population is the length of sentences. One country might imprison less people but for much longer so the total population at one time might be very high.

I think it's a sign of horrible reasons. Dig into specifics and the US does unjustly keep people in prison on a regular basis.

We have huge issues from generations of politics over substance. It's only obvious that things are getting worse when you look at statistics because nobody has unbiased understanding of the entire system.

if you imprison 1 person for no reason at all, that would be pretty horrible... but if you imprison thousands for barely nothing, that is ok?