Frequencies for first 10,000 rows of exercise variable in nhamcsopd2001 dataset : exercise | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,476 94.76 94.76 1 | 524 5.24 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016