Frequencies for first 10,000 rows of visual variable in nhamcsopd1996 dataset : visual | acuity | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,603 96.03 96.03 1 | 397 3.97 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016