Frequencies for first 10,000 rows of cardiac variable in natl1992 dataset : Cardiac | disease | Freq. Percent Cum. ------------+----------------------------------- 1 | 13 0.13 0.13 2 | 9,961 99.61 99.74 9 | 26 0.26 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Dec 2015