The EU isn't prolific with regulations. Most of the regulations it passes already exist in member states, and the EU is just harmonizing them across the continent.
The classic example of this is the "straight bananas" myth. The rules were already in effect in the UK and most other EU countries, because they were an international de-facto standard used by banana producers and banana consumers. When the EU harmonized nothing actually changed in the UK - no new laws, no changes to standard or regulations, nothing. But what were once UK rules suddenly had an EU stamp on them, and were branded as silly and excessive.
This also illustrates the difficulty in determining what is an EU regulation. Given that the UK already had the same rules anyway, do rules covering bananas count as EU regs?
Based on a BBC investigation of the issue, the amount of UK law that is derived from EU regulations could be as low as 13%.