Frequencies for first 10,000 rows of nprev12 variable in natl1978 dataset :

  Number of |
   Prenatal |
     Visits |
     Recode |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        124        1.24        1.24
          2 |        321        3.21        4.45
          3 |        659        6.59       11.04
          4 |      1,143       11.43       22.47
          5 |      1,206       12.06       34.53
          6 |      1,839       18.39       52.92
          7 |      2,539       25.39       78.31
          8 |      1,322       13.22       91.53
          9 |        521        5.21       96.74
         10 |        115        1.15       97.89
         11 |        125        1.25       99.14
         12 |         86        0.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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