Frequencies for first 10,000 rows of dlmp_yy variable in natl2009 dataset :

Last Normal |
   Menses - |
   Year U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
       2008 |      7,834       78.34       78.34
       2009 |      2,028       20.28       98.62
       9999 |        138        1.38      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015