Frequencies for first 10,000 rows of nprevis variable in natl1988 dataset :

      Total |
  Number of |
   Prenatal |
     Visits |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        206        2.06        2.06
          1 |         69        0.69        2.75
          2 |        109        1.09        3.84
          3 |        155        1.55        5.39
          4 |        227        2.27        7.66
          5 |        260        2.60       10.26
          6 |        357        3.57       13.83
          7 |        380        3.80       17.63
          8 |        551        5.51       23.14
          9 |        600        6.00       29.14
         10 |      1,147       11.47       40.61
         11 |        881        8.81       49.42
         12 |      1,644       16.44       65.86
         13 |        845        8.45       74.31
         14 |        776        7.76       82.07
         15 |        586        5.86       87.93
         16 |        338        3.38       91.31
         17 |        150        1.50       92.81
         18 |        109        1.09       93.90
         19 |         54        0.54       94.44
         20 |        121        1.21       95.65
         21 |         14        0.14       95.79
         22 |         17        0.17       95.96
         23 |         10        0.10       96.06
         24 |         18        0.18       96.24
         25 |         20        0.20       96.44
         26 |          5        0.05       96.49
         28 |          2        0.02       96.51
         30 |         17        0.17       96.68
         32 |          1        0.01       96.69
         33 |          2        0.02       96.71
         34 |          2        0.02       96.73
         35 |          1        0.01       96.74
         36 |          1        0.01       96.75
         38 |          1        0.01       96.76
         39 |          1        0.01       96.77
         41 |          1        0.01       96.78
         49 |          2        0.02       96.80
         99 |        320        3.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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