Frequencies for first 10,000 rows of f_u_forcep variable in natlterr2006 dataset : Forceps | (ume_forcep | ) U | Freq. Percent Cum. ------------+----------------------------------- 0 | 1,468 14.68 14.68 1 | 8,532 85.32 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 22 Dec 2015