FWIW, the March 2013 (pre-acquisition) version of this same report [1] ranked Y! at #2 with 191 million, 5 million short of the July figure. For comparison to other gains during that same time, Microsoft gained 13 million, Ask gained 4 million, and Tumblr gained 9 million.

[1] PDF @ http://www.comscore.com/content/download/20239/1035515/file/...