Most likely the incidence of OCD has not increased in the last decade, what has increased is an awareness of it. As more therapists become familiar with OCD and how to treat it, there will be more diagnoses of OCD. But just because more people are diagnosed with OCD does not mean that the incidence of it is increasing, people diagnosed with OCD would have had it regardless of whether it was recognized by a doctor or not. Though more people may be diagnosed correctly with OCD, there will most likely be a decrease in the diagnoses that OCD might have been otherwise diagnosed as, such as tic disorders. This will be an interesting area for future research.
This is currently happening with autism and mental retardation. While many families who have children diagnosed with autism are saying that the diagnosis of autism is on an alarmingly increasing upswing, the diagnosis of mental retardation appears to be on a steep decline (Croen, Grether, Hoogstrate, and Selvin, 2004). This may be because those children who were once diagnosed with mental retardation are now being more accurately diagnosed with autism. As we continue to learn more about individual disorders and how to differentiate them, statistics will shift in many areas.