Frequencies for first 10,000 rows of nprevis variable in natl1976 dataset :

      Total |
  Number of |
   Prenatal |
     Visits |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        122        1.22        1.22
          1 |        164        1.64        2.86
          2 |        187        1.87        4.73
          3 |        279        2.79        7.52
          4 |        440        4.40       11.92
          5 |        468        4.68       16.60
          6 |        600        6.00       22.60
          7 |        580        5.80       28.40
          8 |        767        7.67       36.07
          9 |        703        7.03       43.10
         10 |      1,236       12.36       55.46
         11 |        709        7.09       62.55
         12 |      1,368       13.68       76.23
         13 |        550        5.50       81.73
         14 |        557        5.57       87.30
         15 |        531        5.31       92.61
         16 |        205        2.05       94.66
         17 |         87        0.87       95.53
         18 |         75        0.75       96.28
         19 |         22        0.22       96.50
         20 |         82        0.82       97.32
         21 |          8        0.08       97.40
         22 |          7        0.07       97.47
         23 |          5        0.05       97.52
         24 |          5        0.05       97.57
         25 |         11        0.11       97.68
         26 |          1        0.01       97.69
         27 |          3        0.03       97.72
         28 |          3        0.03       97.75
         29 |          1        0.01       97.76
         30 |          8        0.08       97.84
         32 |          2        0.02       97.86
         37 |          1        0.01       97.87
         49 |          1        0.01       97.88
         99 |        212        2.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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