Birth cohort was categorized into three groups (Figure S1)1 (U.S. Department of Health Human Services, 2014): (1) those born before 1945, a period of low but increasing cigarette consumption; (2) those born 1945–1975, the period of highest per capita cigarette consumption that peaked around the 1964 report (U.S. Surgeon General’s Advisory Committee on Smoking and Health); and (3) those born after 1975, when cigarette consumption steadily declined.
