"As a matter of fact, the number of schools and school districts actually implementing drug-testing programs is relatively small although not insignificant. From 1998 through 2001, the percentage ranged from just over 14% of schools, peaking at just over 23% in 2000 then down to approximately 16% in 2001.50 According to a 2006 survey, approximately 12% of the nation’s school districts had testing programs with an additional 10% considering them.51"

Source

Stuart, Susan P., "When the Cure is Worse than the Disease: Student Random Drug Testing & Its Empirical Failure," Valparaiso University Law Review (Valparaiso, IN: Valparaiso University Law School, 2010), Volume 44, Number 4, p. 1065.
http://scholar.valpo.edu/cgi/…