I have been having seizures for over a year and have finally been diagnosed w epilepsy. i am 39. how common is this?

Less common: Large number of epilepsies present in childhood and adolescence, and perhaps in early twenties; later, in late 50's and older another peak in incidence occurs. So, in your case, less frequent onset. But, you may have had head trauma, an infection, or contact with recreational drugs or alcohol nutritional issues, even co-morbidity with migraine. Glad diagnosis has been reached, and rx started.