Frequencies for first 10,000 rows of mm_mtr variable in natl2014 dataset :

   Maternal |
Transfusion |
      Y Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,769       97.69       97.69
          U |        184        1.84       99.53
          Y |         47        0.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016