A national survey has found there's been a sharp drop in the percentage of America's children being bullied or beaten up by their peers.

The survey's authors say it may be evidence anti-bullying programs at thousands of schools are having an impact.

The study was funded by the U.S. Department of Justice and was conducted by the University of New Hampshire's Crimes Against Children Research Center. It found the percentage of children who reported being physically bullied over the previous year had declined from nearly 22 percent in 2003 to under 15 percent in 2008.

Professor David Finkelhor was the lead author of the study. He notes anti-bullying programs spread following the 1999 Columbine High School shootings in Colorado.