Substance Use B Alcohol: (Data from the 1999 Ontario Student Drug Use Survey carried out by the Centre for Addictions and Mental Health for Ontario youth in grades 7 through 13). In 1999, 19.7% of drinkers drank weekly, a significant increase from 17.1% in 1997 and 14.4% in 1993. In 1999, 67.5% of all students reported drinking during the previous 12 months. Past year drinking was higher for males than females (70.7% vas 64.2%), and varied by grade (increasing from 39.7% of 7th graders to 84.6% of 12th graders). The percentage of drinkers increased significantly from 1997 to 1999 among the total sample (59.6% to 65.7%). Increases in past year drinking were especially notable since 1993.