Nielsen Online has released its rankings of U.S. search share for May (PDF). Overall search increased 20.3 percent year over year to 9.4 billion searches. Google had year over year increase of 28.2 percent and received 63.2 percent of searches. Yahoo had a year over year increase of 22.3 percent and received 17.2 percent of searches. Microsoft had a year over year decrease of 14.6 percent and received 9.4 percent of searches.