Hitwise and Nielsen/NetRatings issued their rankings of the top search providers for August, based on search volume, with the usual suspects at the very top of their respective lists - and the usual divergence in search-share proportions, as well as in the rankings below the top 3 - reports MarketingCharts.

An estimated 4.2 billion search queries were conducted at Google Search, accounting for 54 percent of all search queries conducted in August, according to NetRatings.

Yahoo Search followed with less than 1.6 billion searches and a 20 percent share, in turn followed by MSN/Windows Live with 1.0 billion searches and 13 percent share of searches, NetRatings said.

Year-over-year growth among the top 3 ranged from 70 percent (MSN/Live Search) to 9 percent (Yahoo); Google's YOY growth was 40 percent.

As usual, Hitwise's search-share data varies from those of NetRatings and once again assigns Google a significantly higher share - 64 percent (for the four weeks ended September 1). In second and third position are Yahoo Search and MSN Search with 23 percent and 8 percent, respectively.

Nielsen/NetRatings and Hitwise disagree regarding which search provider is in fourth place: The former gives AOL Search a 5.6 percent share, whereas the latter assigns fourth place to Ask.com with 3.4 percent share. NetRatings ranks Ask fifth, with 1.7 percent share.

The remaining 48 search engines in the Hitwise Search Engine Analysis Tool accounted for 1.68 percent of US searches, Hitwise said. NetRatings assigned a combined 2.6 percent to the search providers in the sixth through tenth positions in its rankings.

Search engines remain the primary way internet users navigate to key industry categories, according to Hitwise, with the Travel, Entertainment, and Business and Finance categories received double-digit increases YOY in their share of traffic coming directly from search engines.

(Also see Compete.com's version of August's search rankings: "Microsoft's Search Surge Stalls in August, Google's Share at Two-Thirds.")