Frequencies for first 10,000 rows of tkbrak_t variable in vindecode dataset : (brake | type) | description | Freq. Percent Cum. ------------+----------------------------------- | 5,731 57.31 57.31 AIR | 645 6.45 63.76 AIR/HYD | 3 0.03 63.79 HYD.-VAC. | 2 0.02 63.81 HYDRAULIC | 2,417 24.17 87.98 Unknown | 1,202 12.02 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Oct 2016