With this information alone, no we cannot tell.

For example if we took random samples of the population and tested them for marijuana usage, what percentage would test positive?

Next, this study is only talking about marijuana testing, how many of the same group also tested positive for alcohol (or other impairing drugs). Lets make up fake numbers and say 60% of total fatalities had alcohol or other impairing drugs and the overlap between them and marijuana use was 80% then marijuana is rather insignificant.

We have to have all the details so we don't fall into a base rate fallacy.