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

      other |
 ultrasound |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,870       98.70       98.70
        yes |        130        1.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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