Frequencies for first 10,000 rows of eimageo variable in nhamcsopd2007 dataset :

   if yes, are |
    electronic |
        images |
     returned? |      Freq.     Percent        Cum.
---------------+-----------------------------------
       unknown |      1,457       14.57       14.57
not applicable |      3,820       38.20       52.77
           yes |      4,001       40.01       92.78
            no |        722        7.22      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016