The decline of teen cigarette smokers
https://www.cdc.gov/tobacco/data_statistics/tables/trends/cig_smoking/
https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4843a2.htm
Teen cigarette smoking rates have been steadily decreasing over the years. This phenomenon is evident from the graph on the CDC page, which plots the percentage of teen smokers from 1965 to 2014. In 1965, up to 42.4% of teens smoked cigarettes, while in 2014, the number shrunk to a mere 16.8%. Though there may be a number of reasons for this trend, the first and most important reason is that the percentage of users dipped below the tipping point and therefore cigarette use is declining towards zero.
Before the dangers of smoking cigarettes was widely known to the public, cigarette companies actively advertised cigarettes as a staple of cool and edgy teens. It can be seen in a CDC graph of the trend in cigarette use of US adults that the popularity of cigarettes was on the rise until 1970. When a product reaches its tipping point, its use increases until it meets an equilibrium point, where its use plateaus.
At around 1970, it was revealed that smoking does cause cancer and this had a huge impact on the tipping point. Teens nowadays have access to better education on the harmful effects of smoking due to the active presence of anti-smoking campaigns that highlight the numerous reasons smoking can be harmful to the human body. There is also a very negative perception of cigarette smokers (that they have bad skin, bad breath, and cough constantly), which also causes people to steer away from smoking.
This caused the percentage of smokers to dip heavily below the tipping point. When a product fails to reach the tipping point, its use declines and eventually reaches zero. However, it is unlikely that cigarette use will truly be eradicated because there will always be niche groups of people who still smoke.