I'm not sure we know that. I think there have been several smoking guns over time related to certain strains of drug-resistant bacteria, but there is a lot of overlap.
In Canada, for medically significant antimicrobial resistance in humans, almost certainly more than half of that resistance is related to human use. It can be very difficult, because there's so much interface between, for example, the food we ingest and resistance that we may acquire from the food that it makes it very difficult to pinpoint it to one. This is why, again, I think all of us believe that taking a one health approach is really important, because there isn't just one problem that needs to be fixed.