Has medical marijuana reduced the reliance on opiates for pain relief in states that have medical mj?

Is there any way to know?

If marijuana is used for pain relief (as people say), has there been any drop in the number of prescriptions written for opiates like hydrocodone, vicoden, etc.?

: http://alcoholdrugstreatment.info/has-medical-marijuana-reduced-the-reliance-on-opiates-for-pain-relief-in-states-that-have-medical-mj