More than 320 free newspapers have been launched so far, and of those, 81 have closed down, Newspaper Innovation reported Monday.

The 25 percent closure rate seems to stem mainly from years with economic recessions.

The two periods with the highest number of closures happened in 2001/2002 and 2006/2007, Newspaper Innovation reported. In 2006 and 2007, closures titles versus editions indicated larger titles closed down more than previous years.

In 2008, so far there have been six closures in the first half of the year, according to Newspaper Innovation.