Recent data from comScore finds that although total search queries continue to increase, paid search clicks are not keeping pace, which may make it more important for companies to consider search engine optimization (SEO).

Gian Fulgoni, chairman and co-founder of comScore writes that search engine queries have risen 68 percent in the last two years, but over that span the amount of clicks to paid search ads had only increased 18 percent.

The reason for this, according to Fulgoni, is that ad coverage has dropped and Fulgoni gives two possible reasons for this drop in ad coverage.

First, Fulgoni says, is that search engines have improved and now return much more relevant results to users.

But a second reason may be the way people are searching. According to Fulgoni, the number of words in a typical search has steadily increased over the last two years with the average search now slightly over three words.

"[T]his apparently reduces the likelihood that an advertiser has bid to have his/her ad included in the results page from these longer queries, due to paid search advertising strategies that limit ad coverage, such as Exact Match, Negative Match, and bid management software campaign optimization," he writes.

Other studies have found that these so called "long tail" keywords are increasing with a report in March from Hitwise finding that over the previous year, searches containing eight or more words had increased 20 percent while searches of four or less had decreased 2 percent.

Both of these explanations should make search engine optimization (SEO) more appealing to organizations looking to increase traffic to their sites.