Figure 2
From: Trends in the prevalence of smoking in Portugal: a systematic review
Trends in the prevalence of smoking in different age group, by sex. Only were considered the results of the studies involving national representative samples of the general population. When a given study provided more than one estimate for each of the age groups computed, we computed the weighted mean of the prevalence of smoking. Studies involving samples with a wide age-range and not presenting age-stratified data were excluded.