This too much info put on a graph for websites regarding google panda update. Though Google says only x% of websites got it, we have no proof for it. As we can gather there are lot of quality websites got hit not just for some of the reasons mentioned above and lot of copy paste websites missed the penalty.
Google have identified a website and gave a penalty to the webmaster not just a particular website. If one website has effected from panda, google penalized all the websites of that webmaster from their google adsense account or even analytics.