Frequencies for first 10,000 rows of breast variable in nhamcsopd1996 dataset : breast exam | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,518 95.18 95.18 1 | 482 4.82 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016