Frequencies for first 10,000 rows of rn variable in nhamcsopd1999 dataset : registered | nurse seen | Freq. Percent Cum. ------------+----------------------------------- 0 | 4,212 42.12 42.12 1 | 5,788 57.88 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016