Frequencies for first 10,000 rows of f_cigs_3 variable in natl2009 dataset : Cigarettes | 3rd | Trimester | (cig_3) R | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,962 99.62 99.62 1 | 38 0.38 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Dec 2015