Frequencies for first 10,000 rows of sch_bus variable in accident dataset : SCHOOLBUS | RELATED | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,964 99.64 99.64 1 | 36 0.36 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 18 Apr 2016