Frequencies for first 10,000 rows of lmpmon variable in natl1980 dataset :

 Month Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         15        0.15        0.15
          2 |         88        0.88        1.03
          3 |      1,225       12.25       13.28
          4 |      3,732       37.32       50.60
          5 |      3,264       32.64       83.24
          6 |      1,211       12.11       95.35
          7 |        227        2.27       97.62
          8 |         47        0.47       98.09
          9 |         14        0.14       98.23
         10 |          7        0.07       98.30
         11 |          9        0.09       98.39
         12 |          7        0.07       98.46
         99 |        154        1.54      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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