Google, Google and, um, Google
Google is by far the most popular search engine in the U.S. Almost 70% of all internet searchers in the U.S. are going to see Google’s results (even though they might not be using Google directly). So Google should be your primary focus when optimizing your acupuncture website.
Other search engines that people use are Yahoo! and Microsoft’s oft renamed search engine, currently known as Bing. A handful of people also use Ask.com, mainly in the South West U.S. And that’s it.
UPDATE: Yahoo now licenses its search results from Bing. That means that Yahoo results will be identical to Bing results.