Google might still be the leading search engine in the U.S. by a large margin, but over the last six months, searches powered by Microsoft Bing are increasing at an impressive rate. So impressive, in fact, that if the trend line continues, there will be a real contest between Bing and Google next year — and Bing may just come out on top.

According to the latest data from Experian Hitwise, Google was responsible for 64.42% of searches in the U.S. in March, 2011. Bing-powered search — which includes both search.yahoo.com and bing.com — accounted for 30% of U.S. searches.

[link to mashable.com]