Frequencies for first 10,000 rows of nprev12 variable in natl1979 dataset :

  Number of |
   Prenatal |
     Visits |
     Recode |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        116        1.16        1.16
          2 |        327        3.27        4.43
          3 |        575        5.75       10.18
          4 |      1,023       10.23       20.41
          5 |      1,211       12.11       32.52
          6 |      2,021       20.21       52.73
          7 |      2,371       23.71       76.44
          8 |      1,333       13.33       89.77
          9 |        647        6.47       96.24
         10 |        142        1.42       97.66
         11 |        130        1.30       98.96
         12 |        104        1.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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