Frequencies for first 10,000 rows of f_ca_limb variable in natl2012 dataset : Limb | Reduction | Defect | (ca_limb) R | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,986 99.86 99.86 1 | 14 0.14 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 5 May 2016