Those data for opiate use, not abuse. I suspect the percentage of the population who have used any opiates at least once in the past year tells you very little about about opiate-related problems - using cocodamol once a year is obviously very different to the habitual use of oxycodone.

I further suspect that the availability of opiate-containing drugs over the counter in some countries accounts for some of the differences in those statistics (e.g. cocodamol in the UK).