Frequencies for first 10,000 rows of lmpyr variable in natl1981 dataset :

  Year Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          - |        199        1.99        1.99
          0 |      9,775       97.75       99.74
          1 |         26        0.26      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016