I just went through ComScore May 2010 Search Rankings. Google remains in the top,but there is 0.7% dip in the marker share. Yahoo & Bing are with 29.5% market share. I am combining both data because of their Yahoo-Microsoft Alliance.

These percentage changes may look very small seeing the first time. But it matters a lot, because the total core search activity for one month in Total U.S is about 15935million searches. Now you can do the Math.