Frequencies for first 10,000 rows of f_uca_rectal variable in natl2006 dataset : Rectal | Atresia/Ste | nosis | (uca_rectal | ) U | Freq. Percent Cum. ------------+----------------------------------- 0 | 13 0.13 0.13 1 | 9,987 99.87 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Dec 2015