Obsessive Compulsive Disorder affects over 4% of the population at different points in their lives. One third of afflicted adults had their first symptoms in childhood, and more boys are afflicted in childhood than girls. Females are more likely to have their first symptoms in adolescence and early adulthood.

Deep Knowledge Reference
"The Economic Burden of Anxiety Disorders", commissioned by the ADAA and published in the Journal of Clinical Psychiatry.