Frequencies for first 10,000 rows of u_apncu variable in natl2004 dataset :

Adequacy of |
   Prenatal |
       Care |
Utilization |
    Index U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,433       14.33       14.33
          2 |      1,681       16.81       31.14
          3 |      3,396       33.96       65.10
          4 |      2,122       21.22       86.32
          9 |      1,368       13.68      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 21 Jan 2016