On Friday, I published a chart showing that, despite dropping crime rates, the rate of people being sentenced in federal court has gone up.
As I mentioned then, one plausible explanation for this mismatch is that there is just something particular about federal crimes (which are a small slice of overall crimes). So I went looking for some state-only data. I was able to find some data on the number of number of felonies filed in Illinois courts each year since 1997. If you add that data, you get this chart:
(All three lines are normalized to an index rate of 100 in 1997, so this shows their relative change over time.)
The blue line is the new Illinois data. Unlike the federal sentencing rate (which has gone up despite the drop in crime) the Illinois felony-filing was steady between 1997 and 2006, after which it began to mirror the drop in the overall crime rate. So that's kind of encouraging. And it's evidence that undercuts my implicit hypothesis that the prosecution rate isn't at all sensitive to the crime rate.