Frequencies for first 10,000 rows of drugtst3 variable in person dataset : Drug Test | -Type (3) | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,445 94.45 94.45 1 | 313 3.13 97.58 2 | 46 0.46 98.04 3 | 12 0.12 98.16 6 | 156 1.56 99.72 8 | 1 0.01 99.73 9 | 27 0.27 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 18 Apr 2016