Frequencies for first 10,000 rows of cardiac variable in natlterr1994 dataset : Cardiac | disease | Freq. Percent Cum. ------------+----------------------------------- 1 | 31 0.31 0.31 2 | 9,957 99.57 99.88 9 | 12 0.12 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Dec 2015