Frequencies for first 10,000 rows of mri variable in nhamcsopd1996 dataset : mri | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,914 99.14 99.14 1 | 86 0.86 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016