At a guess the declining rate is because DNA testing came online in a big way from that point on. It's become a lot easier to identify property crimes in particular because shitheads might not leave fingerprints behind, but they often leave blood when they bust in windows. You're more likely to commit a crime if you think you're going to get away with it.
Remissas, discite, vivet.
God save us from people who mean well. -storm