Frequencies for first 10,000 rows of lmpyr variable in natlterr1998 dataset :

  Year Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
       1997 |      9,879       98.79       98.79
       9999 |        121        1.21      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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