Non-Indo-European in Greek

Hello, I was just curious as to opinion regarding the non-Indo-European element in ancient Greek vocabulary (around 30% of the vocabulary if I'm not mistaken, I believe Germanic has a similar proportion of non IE) with regards to the ancient ethnic population. In artistic representations from the Mycenaean period (especially wall paintings) the Greeks of this period look very different (from Greeks of the Classical period), looking less "European" (for lack of a better term) and more "Near Eastern". This makes me wonder if during the Bronze Age the proportion of ethnic Indo-European Greeks was less than in later periods, perhaps larger numbers of Indo-European speakers migrated to Greece during the "Dark Ages" and "Dorian Migrations".

-Michael