Frequencies for first 10,000 rows of mm_mtr variable in natlterr2013 dataset :

   Maternal |
Transfusion |
622=f_mm_mt |
     rans R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      1,077       10.77       10.77
          N |      8,487       84.87       95.64
          U |        428        4.28       99.92
          Y |          8        0.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015