http://www.cdc.gov/mmwr/preview/mmwrhtml/00021062.htm

To characterize the patterns of attempting to quit smoking and smoking cessation among U.S. adults during 1990 and 1991, CDC's National Health Interview Survey-Health Promotion and Disease Prevention (NHIS-HPDP) supplement collected self-reported information on cigarette smoking from a representative sample of the U.S. civilian, noninstitutionalized population aged greater than or equal to 18 years. This report summarizes findings from this survey.