Occurrence of violence among 12-18-year-old adolescents in 1999 and 2009 in Finland.

We examined whether the occurrence of violence changed among Finnish adolescents between 1999 and 2009. The study was based on the nationwide Adolescent Health and Lifestyle Survey from samples of 12- to 18-year-olds. The number of respondents was 8136 in 1999 and 5516 in 2009. The proportion of adolescents reporting violence was 7.9% in 1999 and 6.2% in 2009 (P < 0.000). In both of the study years, the violence occurrence rate varied by age and sex, with boys reporting higher rates in all age groups. The results did not support our hypothesis of a general increase in violence among adolescents.