I think you are misunderstanding the figure, it is 72 pill/year/person, so if an average person with a prescription is taking 2-4 (let's just use 3) they will need 365*3 = 1095 pills/year. That rate of consumption implies that 72/1095 = 6.5% of the total population is on a never ending prescription for opiates.
As a percentage of the population, that still seems really high, but WV is taking 0.2 pills/person/day not 2-4 pills/person/day