Frequencies for first 10,000 rows of ctunk variable in nhamcsed2007 dataset :

  ct scan - |
   site not |
  specified |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,854       98.54       98.54
          1 |        146        1.46      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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