<unk>  is reported by the World Health Organization (WHO), which focuses on cigarette smoking due to reported data limitations. Smoking has therefore been studied more extensively than any other form of consumption. Smoking is generally five times more prevalent among men than women; however, the gender gap differs across countries and is smaller in younger age groups. In developed countries smoking rates for men have peaked and have begun to decline, and also started to stall or decline for women. Smoking prevalence has changed little since the mid-1990s, before which time it declined in English-speaking countries due to the implementation of<unk>  control. However, the number of smokers worldwide has increased from 721 million in 1980 to 967 million in 2012 and the number of cigarettes smoked increased from 4.96 trillion to 6.25 trillion due to population growth. In Western countries, smoking is more prevalent among populations with mental health problems, with alcohol and drug problems, among criminals, and among the homeless. In 2002, about 20% of young teens (aged 13–15) smoked worldwide. 80,000 to 100,000 children begin smoking every day. Half of those who begin smoking in adolescent years are projected to go on to smoke for 15 to 20 years. One of the targets of the Sustainable Development Goal 3 of the United Nations (to be achieved by 2030) is to "Strengthen the implementation of the World Health Organization Framework Convention on<unk>  Control in all countries, as appropriate." The indicator that is<unk> d to measure progress is the<unk> .
Prevalence of tobacco use
Prevalence of mental disorders
Smoking in South Korea
Prevalence of birth control
History of medical diagnosis
Prevalence of teenage pregnancy
History of virology
Epidemiology of childhood obesity