Frequencies for first 10,000 rows of pps_period variable in psfhos201207 dataset : Provider | PPS Period | (Not Used | as of | 4/1/91) | Freq. Percent Cum. ------------+----------------------------------- | 9,792 97.92 97.92 0 | 208 2.08 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 17 Feb 2018