Frequencies for first 10,000 rows of mrcnty variable in natl2008 dataset :

   Mother's |
  County of |
  Residence |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          . |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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