Frequencies for first 10,000 rows of uca_spina variable in natl2015 dataset :

      Spina |
   Bifida / |
Meningocele |
  1 Anomaly |
   reported |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          1        0.01        0.01
          2 |      9,998       99.98       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Oct 2016