Frequencies for first 10,000 rows of breast variable in nhamcsopd1998 dataset : breast exam | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,282 92.82 92.82 1 | 718 7.18 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016