Frequencies for first 10,000 rows of mricontrast variable in nhamcsed2015 datas

       Was MRI |
ordered/provid |
       ed with |
   intravenous |
 (IV) contrast |      Freq.     Percent        Cum.
---------------+-----------------------------------
         Blank |      9,936       99.36       99.36
       Unknown |         24        0.24       99.60
           Yes |          6        0.06       99.66
            No |         34        0.34      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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