Frequencies for first 10,000 rows of prov1770 variable in pos1991 dataset :

      renal |
 transplant |
center code |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,949       99.49       99.49
          A |         49        0.49       99.98
          B |          1        0.01       99.99
          C |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 26 Jan 2016