You might check with:
http://www.greencarcongress.com/
They've been following the production numbers and would be the most authoritative source for hybrid sales. However, I don't think anyone knows how many have been lost to accidents or otherwise retired.
Be careful about the definition of a hybrid. The belt-assisted hybrid are especially weak and looked to be more of a marketing ploy than serious engineering. This is based upon how much 'tax credit' respective vehicles were getting. Belt-assisted is better than nothing but lacks the ability to move on electric-only. I understand the IMA has electric-only, not from a dead stop, but in a sustaining momentum mode (I'm not an expert in this and could use some help.)
Bob Wilson