The article says in the 60's 40% of Americans smoked and now it's down to 11%. Meaning in the 60's 40% of Americans were on stimulants and now it's down. What

The article says in the 60's 40% of Americans smoked and now it's down to 11%. Meaning in the 60's 40% of Americans were on stimulants and now it's down. What affect does having so much of the population on stimulants have? What affect does having much fewer of the population on stimulants have?