If you take tramadol as prescribed(50 mg 4times daily for ex.) how long will it take to become addicted.?

I would hate to end up trying to cop trams on the street especially since there not that good. I hope 200mg a day wont cause me to be an addict. Ive been taking them for a month without missing a dose. Can i get some info. from anyone who is on them or is in the medical profession.