Yes, OL -- and records before then were 100% honest?
We've seen in the case of Jimmy Saville that not all crimes, even horrific ones, get reported honestly. I don't see that changing for a while, there will always be unreported crimes. It's pure cynicism to assume that the police lying about it started only ten years ago.
There are two things I think it is safe to say:
1) Crime rates fluctuate over time.
2) Crimes rates overall are relatively stable.
In this case, we have seen over the 50 years following WWII, or so, an apparent rise in violent crime. That rise did not continue before then indefinitely. Otherwise, logically, AOG's day was much more dangerous than a generation or so previously in kind.
It appears to be the case that crime rates are falling of late. That's not entirely unreasonable. Things don't continually get worse.