Frequencies for first 10,000 rows of lmpyr variable in natlterr1999 dataset :

  Year Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
       1998 |      9,806       98.06       98.06
       9999 |        194        1.94      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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