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

      Total |
  Number of |
   Prenatal |
     Visits |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        124        1.24        1.24
          1 |        123        1.23        2.47
          2 |        198        1.98        4.45
          3 |        269        2.69        7.14
          4 |        390        3.90       11.04
          5 |        487        4.87       15.91
          6 |        656        6.56       22.47
          7 |        525        5.25       27.72
          8 |        681        6.81       34.53
          9 |        697        6.97       41.50
         10 |      1,142       11.42       52.92
         11 |        933        9.33       62.25
         12 |      1,606       16.06       78.31
         13 |        592        5.92       84.23
         14 |        730        7.30       91.53
         15 |        388        3.88       95.41
         16 |        133        1.33       96.74
         17 |         44        0.44       97.18
         18 |         71        0.71       97.89
         19 |         10        0.10       97.99
         20 |         68        0.68       98.67
         21 |          8        0.08       98.75
         22 |         14        0.14       98.89
         23 |          2        0.02       98.91
         24 |          1        0.01       98.92
         25 |         13        0.13       99.05
         30 |          7        0.07       99.12
         33 |          1        0.01       99.13
         38 |          1        0.01       99.14
         99 |         86        0.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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