Interestingly, according to this PDF from ETS, of states that accept or want the Praxis II test that I took ("Mathematics Content"), Colorado's required score of 156 is the highest. (A score of 165 apparently qualifies you for a "recognition of excellence" from ETS.) The median required score to pass, among states that use this test, is 136.
In 2004-2005 at least, apparently the median score on the exam was 143, and what Praxis calls the "average range" was 127-156. I'm not sure what an "average range" is. (The possible scores on this test go from 100 to 200.)
Anyway, here is a map showing the required passing scores for the various states. I left out Guam, but for the record you need a 124 to pass this in Guam.
Click to embiggen.
I suspect the reason that Colorado wants such a "high" Praxis II score is that they'd prefer you to take the Colorado-specific PLACE test instead, which is more specific (I guess) to their needs. So if you insist on having the Praxis instead, they want a really good one.