Frequencies for first 10,000 rows of eimgres variable in namcs2007 dataset :

  practice has |
      computer |
    system for |
       viewing |
       imaging |
      results? |      Freq.     Percent        Cum.
---------------+-----------------------------------
         blank |          9        0.09        0.09
       unknown |        184        1.84        1.93
           yes |      3,803       38.03       39.96
            no |      5,901       59.01       98.97
    turned off |        103        1.03      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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