Frequencies for first 10,000 rows of centline variable in nhamcsed2013 dataset :

    Central |
       line |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,867       98.67       98.67
        Yes |        133        1.33      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 7 Nov 2016