The collecting criteria may have changed though.
In 30 years it will have, without a doubt.
And? You're inferring something, but not actually stating what you're inferring. Are you saying that crime is getting worse, but that the figures are massaged in the way they're collected?
I'm unsure what your point is. If you read the link it covers pretty much the whole subject in a nice bite-sized read. It even covers how our perception of what crime rates are and how the reality of the situation may differ.
But if you look to the countries with the lowest re-offending rates, you'll see they're modern countries that treat their convicts with some degree of respect. If you know of any examples where harsh prison regimes reduce re-offending, I'd be interested to read about it.