Oh search sure, but I thought they would get more views on things like DoubleClick ads embedded in other pages.
Searches are also what drive relevance on other pages' embedded ads. Because you search on Google, they know how to target ads when you are browsing elsewhere.
Google websites include search as well as YouTube, Gmail, et cetera. AdSense, AdMob or DoubleClick revenues make up the bulk of the other 20%.
[1] https://www.sec.gov/Archives/edgar/data/1652044/000165204416... pages 31, 33
(Also most people honestly don't know the difference between sponsored results and real search results)