I'd be surprised if more than 5% (probably even less) of the population should be on heavy painkillers at any given time. I don't know statistics from other countries but we're talking about pills that are being used to treat severe pain, not just a headache.
2x Opiod pain pills a day every day for an entire year is a very serious amount of pain if legitimate.
If a state were to legitimately have 10% of its population that badly hurting, there should be a huge governmental investigation into what factor is causing that much crippling pain.
