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

    Date of |
Last Normal |
 Menses (by |
State) flag |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |          9        0.09        0.09
          1 |      9,991       99.91      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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