It's an old argument; how many laws originate from the EU? Daniel Hannan says 85%, UKIP say 75%, Cameron says half, Labour MPs; Tom Harris, Kerry McCarthy, and Caroline Flint often misleadingly use this House of Commons report to cite 9.1%, as does Left Foot Forward (the report appears to be no longer to be available but it was based on statutory instruments only, so the figure is almost certainly higher in total).
However it's an argument that has won the (misguided) europhile blogger Nosemonkey an award for this marvelous post on the percentage issue. Congratulations to him. The truth is, as he argues, that no-one really knows for sure, but he points me to this recent research paper here. I haven't read it yet mainly due to the consumption of copious quantities of beer - trying to negate the effects of the ridiculous manner of my team losing in the last minute today 5-4.
Suffice to say, for me, the percentage issue is, and always has been, a red herring (rather like the europhiles' obsession with so-called myths).
Any figure is merely an artificial arbitrary line. The argument becomes reduced to one where a certain percentage must mean the EU is good whereas another percentage must mean it's bad. Where to draw the line; 3.1415926535%, 9.1%, 10.7%, 20.8%, 50.346792%, 90.999%?
Quite simply it matters not. The EU is more insidious than the odd food regulation or 'myth' - the point is that 100% of our laws should be made by a democratically elected parliament, and 0% made by an fundamentally undemocratic and corrupt institution.