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

  Admission |
  to NICU Y |
        Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,008       90.08       90.08
          U |         72        0.72       90.80
          Y |        920        9.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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