Frequencies for first 10,000 rows of ultrasnd variable in nhamcsed2015 dataset 

 Ultrasound |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,494       94.94       94.94
        Yes |        506        5.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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