Frequencies for first 10,000 rows of exercise variable in nhamcsopd2007 dataset : exercise | Freq. Percent Cum. ------------+----------------------------------- no | 9,260 92.60 92.60 yes | 740 7.40 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016