Frequencies for first 10,000 rows of lmpday variable in natl1987 dataset :

   Day Last |
     Normal |
     Menses |
      Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        470        4.70        4.70
          2 |        201        2.01        6.71
          3 |        269        2.69        9.40
          4 |        238        2.38       11.78
          5 |        359        3.59       15.37
          6 |        233        2.33       17.70
          7 |        245        2.45       20.15
          8 |        222        2.22       22.37
          9 |        192        1.92       24.29
         10 |        374        3.74       28.03
         11 |        178        1.78       29.81
         12 |        255        2.55       32.36
         13 |        199        1.99       34.35
         14 |        230        2.30       36.65
         15 |        629        6.29       42.94
         16 |        209        2.09       45.03
         17 |        222        2.22       47.25
         18 |        263        2.63       49.88
         19 |        200        2.00       51.88
         20 |        385        3.85       55.73
         21 |        238        2.38       58.11
         22 |        218        2.18       60.29
         23 |        209        2.09       62.38
         24 |        227        2.27       64.65
         25 |        340        3.40       68.05
         26 |        211        2.11       70.16
         27 |        205        2.05       72.21
         28 |        314        3.14       75.35
         29 |        143        1.43       76.78
         30 |        193        1.93       78.71
         31 |         74        0.74       79.45
         99 |      2,055       20.55      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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