Frequencies for first 10,000 rows of nationalpdp variable in ma2013 dataset :

   National |
        PDP |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,739       97.39       97.39
          Y |        261        2.61      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 14 Apr 2016