Frequencies for first 10,000 rows of mm_mtr variable in natlterr2014 dataset :

   Maternal |
Transfusion |
      Y Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      1,077       10.77       10.77
          N |      8,680       86.80       97.57
          U |        216        2.16       99.73
          Y |         27        0.27      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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