Frequencies for first 10,000 rows of repeac variable in natl1999 dataset : Repeat | C-section | Freq. Percent Cum. ------------+----------------------------------- 1 | 870 8.70 8.70 2 | 9,104 91.04 99.74 9 | 26 0.26 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Dec 2015