Frequencies for first 10,000 rows of lmpmon variable in natl1976 dataset :

 Month Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         15        0.15        0.15
          2 |         97        0.97        1.12
          3 |      1,183       11.83       12.95
          4 |      3,676       36.76       49.71
          5 |      3,206       32.06       81.77
          6 |      1,344       13.44       95.21
          7 |        237        2.37       97.58
          8 |         53        0.53       98.11
          9 |         15        0.15       98.26
         10 |          7        0.07       98.33
         11 |          3        0.03       98.36
         12 |         10        0.10       98.46
         99 |        154        1.54      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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