Just doing some research on click through rates as part of a sales pitch for Ad words vs Organic SEO.

The stats I have found are:
There is a 3% click through average on paid ads compared to organically being on number 1 = 36.4%, number 2 = 12.5%, number 3 = 9.5%

The organic results were sourced from this site and verified by this study
However for paid adds, even though I have read about the 3% click through average many times there is no hard evidence/study backing this up.

Does anyone have any solid research on click through averages for paid ads?

Also if anyone has contrary evidence to the organic research I would be happy to see it.