Frequencies for first 10,000 rows of urf_eclam variable in natl2009 dataset :

  Eclampsia |
        RFP |
690=f_urf_e |
  clamp U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         54        0.54        0.54
          2 |      9,935       99.35       99.89
          9 |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015