There's the study that Dr. Weiss referred to earlier. There's a systematic study of decriminalization, a three-year study, with very clear indicators and metrics that are meant to inform about successes, risks and benefits of the initiative—effectively, the answer to the question you're asking.
At the time of issuing the exemption, the government was very clear in saying that it wants to learn as much as it can from this experience and that it would be prepared to act and adjust in response to the information that would be provided. To my knowledge, that's still the policy.