That document pretty explicitly says it has no idea if the statistic is linked to drug policy.

However, even if we posit that the correlation is significant, I'm not sure what you can read into this. While comparatively enlightened, Portugal did not legalize drug possession and didn't decriminalize vending of drugs. So organized crime is still the one making (and fighting over) all the money.

To this day, the best example of the social effects of repealing prohibition is the repeal of Prohibition.