Frequencies for first 10,000 rows of tow_veh variable in vehicle dataset : Towed | Trailing | Unit | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,924 99.24 99.24 1 | 76 0.76 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Apr 2016