Frequencies for first 10,000 rows of lmpyr variable in natlterr1996 dataset :

  Year Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
       1995 |      9,871       98.71       98.71
       1996 |          1        0.01       98.72
       9999 |        128        1.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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