Frequencies for first 10,000 rows of mm_mtr variable in natl2017 dataset :

   Maternal |
Transfusion |
      Y Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,885       98.85       98.85
          U |         57        0.57       99.42
          Y |         58        0.58      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Sep 2018