The number in the headline is quite surprisingly high, I feel, as revealed by this survey reported on by japan.internet.com and conducted by Marsh Inc into web filtering. The survey was specifically looking at service for blocking web pages with content deemed to be harmful.
Between the 1st and 4th of August 2008 300 members of the Marsh online monitor group completed a private internet-based questionnaire. The sample was split 50:50 male and female, and 20:20:20:20:20 of people in their twenties, thirties, forties, fifties and sixty or older.
Sadly, details of why people use filtering services was not described. What it for protection from viruses, to stop their children accessing unsuitable material, or what? Without purchasing the full survey results we will never know.