Experts caution that reliable and up-to-date statistics on student violence against teachers can be hard to acquire. National and district data, however, show a drop in such violence over the past decade. The National Center for Education Statistics' 2007 school crime and safety report, the only known source for such data nationwide, says the proportion of public school teachers physically attacked by students dropped from 3.9 percent in the 1999-2000 school year to 3.4 percent in the 2003-04 school year. Some districts say their own, more recent figures mirror that nationwide decline. School districts cite a variety of steps they have taken, including training teachers to better handle angry students, adding security in schools, and improving the reporting of violent attacks. Still, given the stakes for schools that report high numbers of student violence under federal law, some safety experts voice skepticism about the downward trend.