SAN SEBASTIAN, SPAIN — Thirty-five percent of all content online at the end of 2007 was pornography, according to a study performed by Spanish IT security firm Optenet.However, although the number of individual adult pages “soared” to 155 million last year, the ratio of porn on the Web actually dropped one percent from the previous year’s levels, Optenet noted.

Following adult content on Optenet’s Web real-estate list was e-commerce, with an 11-percent share of all pages; forums with a 7.3-percent share; travel and advertising with a 7-percent share each; sports with 4.5-percent; education with 2.09-percent and music at 1.84-percent.

Optenet said it was concerned about “alarming” increases in the number of pages devoted to some categories of content. According to the company’s survey, websites described as “pro anorexia and bulimia” increased by an astonishing 470-percent, pages devoted to violent content increased 125-percent, racism-oriented sites increased by 70-percent and child sexual abuse sites increased by 18.4-percent. However, Optenet was quick to add that since the number of Web pages virtually doubled between 2006 and 2007, even astronomical increases in some content categories represented only a few additional pages.

Optenet conducts its annual Web content survey using a proprietary traffic-analysis and classification engine that combines artificial intelligence with traditional content filtering technology to categorize website content.