Frequencies for first 10,000 rows of mri variable in nhamcsed1998 dataset : mri | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,983 99.83 99.83 1 | 17 0.17 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016