Search Engine Market Share and Web Site Traffic

An interesting article in today's issue of USA Today Money section (unfortunately not on-line article to link to). It's a story about the rise, fall and future of Yahoo.

I won't go into details of the article, but the article itself contained the following information:

Search Engine Market Share for December in the USA
1. Google 4 Billion searches Market Share 56%
2. Yahoo 1.27 Billion searches Market Share 18%
3. MSN 995 Million searches Market Share 14%
4. AOL 340 Million searches Market Share 4.7%
5. ASK.com 160 Million searches Market Share 2.2%

Source Nielsen Online

So is it any surprise when working on an SEO project that in virtually all cases we only concentrate on Google?