Frequencies for first 10,000 rows of mm_mtr variable in natl2013 dataset :

   Maternal |
Transfusion |
622=f_mm_mt |
     rans R |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,722       97.22       97.22
          U |        227        2.27       99.49
          Y |         51        0.51      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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