Newspapers who are curious about why their classified revenues are down need look no further than this study: According to Pew research, online classified use is growing significantly. The number of online adults to use classified ads websites, such as Craigslist, has more than doubled since 2005. Online classified use has more than doubled in the past four years. Almost half (49 percent) of Internet users say they have ever used online classified sites, compared with 22 percent of online adults who had done so in 2005. On any given day about a tenth of internet users (9 percent) visit online classified sites, up from 4 percent in 2005.