It's kind of a clunky sentence, too

Ouf! That sentence was copyrighted!!! You flattened the intent of what I meant to say. (tears) smile The point is, it may be clunky but it is supposed to make clear that this phenomenen has been going on for years. Many, but still a minor part could not write correct Dutch. Now that this part has become the larger part mesurements have been taken.

That wasn't clear? Then: clunky sentence! Throw it away! (grin)

Your sentence is perfect of course but it does not cover the poor load.