Frequencies for first 10,000 rows of ctcontrast variable in nhamcsed2015 datase

   Was CT Scan |
ordered/provid |
       ed with |
   intravenous |
(IV) contrast? |      Freq.     Percent        Cum.
---------------+-----------------------------------
         Blank |      8,404       84.04       84.04
       Unknown |        226        2.26       86.30
           Yes |        467        4.67       90.97
            No |        903        9.03      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Nov 2017