Frequencies for first 10,000 rows of nprevis variable in natl1989 dataset :

      Total |
  Number of |
   Prenatal |
     Visits |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        165        1.65        1.65
          1 |         62        0.62        2.27
          2 |         88        0.88        3.15
          3 |        104        1.04        4.19
          4 |        210        2.10        6.29
          5 |        289        2.89        9.18
          6 |        315        3.15       12.33
          7 |        334        3.34       15.67
          8 |        621        6.21       21.88
          9 |        486        4.86       26.74
         10 |      1,332       13.32       40.06
         11 |        900        9.00       49.06
         12 |      2,031       20.31       69.37
         13 |        689        6.89       76.26
         14 |        795        7.95       84.21
         15 |        540        5.40       89.61
         16 |        328        3.28       92.89
         17 |        134        1.34       94.23
         18 |         89        0.89       95.12
         19 |         53        0.53       95.65
         20 |        106        1.06       96.71
         21 |         14        0.14       96.85
         22 |         12        0.12       96.97
         23 |          8        0.08       97.05
         24 |         13        0.13       97.18
         25 |         26        0.26       97.44
         26 |          7        0.07       97.51
         27 |          1        0.01       97.52
         28 |          4        0.04       97.56
         30 |         12        0.12       97.68
         31 |          4        0.04       97.72
         32 |          2        0.02       97.74
         33 |          1        0.01       97.75
         34 |          1        0.01       97.76
         37 |          1        0.01       97.77
         49 |          1        0.01       97.78
         99 |        222        2.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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