Frequencies for first 10,000 rows of blank1 variable in nhamcsed2012 dataset :

   Reserved |
        for |
   possible |
 future use |      Freq.     Percent        Cum.
------------+-----------------------------------
      Blank |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 7 Nov 2016