Legit hookskips count as touch and go's for the GPA, assuming your pass wasn't garbage to begin with and caused it yourself. You won't know it since all you hear is "BOLTER BOLTER BOLTER" to make you go into panic mode and give the power the business. Hookskips happen because the hook isn't held down all the way due to a leaky dashpot or just a higher then normal rate of descent at impact or just shit happens. Since I haven't flown the hummer yet I've heard you need to keep the nose from hitting the deck to help out the hook from raising but I think that's just an Hawkeye/COD -ism but at least in the Goshawk, you were going to a nose high attitude instantly anyway so it's a moot point.
As far as number's go, I have no idea nor do I know if real stats are kept, it's rare but it does happen. I know I didn't get any, nor did anyone else in my boat, but I've heard a few guys saying they had one.