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

 Month Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         12        0.12        0.12
          2 |         83        0.83        0.95
          3 |      1,223       12.23       13.18
          4 |      3,782       37.82       51.00
          5 |      3,186       31.86       82.86
          6 |      1,242       12.42       95.28
          7 |        227        2.27       97.55
          8 |         42        0.42       97.97
          9 |         16        0.16       98.13
         10 |          4        0.04       98.17
         11 |          5        0.05       98.22
         12 |          9        0.09       98.31
         99 |        169        1.69      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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