Frequencies for first 10,000 rows of nprev12 variable in natl1981 dataset :

  Number of |
   Prenatal |
     Visits |
     Recode |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        142        1.42        1.42
          2 |        381        3.81        5.23
          3 |        518        5.18       10.41
          4 |        816        8.16       18.57
          5 |      1,157       11.57       30.14
          6 |      1,860       18.60       48.74
          7 |      2,439       24.39       73.13
          8 |      1,491       14.91       88.04
          9 |        753        7.53       95.57
         10 |        168        1.68       97.25
         11 |        188        1.88       99.13
         12 |         87        0.87      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016