I agree shop lifting is a major problem, has been for years and is getting worse. That is partly due to stupid changes in the way it is (or is not) dealt with, the cost of living and a change in social attitude to it that mean some see it as a victimless crime. However that does not change the fact that overall crime is on a downward trend.
are there any reliable stats showing overall crime is on a downward trend ?
there are lots of stats showing RECORDED crime is on a downward trend - they are not the same thing
Shoplifting is just one example there are literally tens of thousands of incidents of shoplifting that are never reported let alone recorded or investigated.
No-one knows how many so by definition there are no reliable stats on overall crime