Frequencies for first 10,000 rows of nprevis variable in natl2001 dataset :

      Total |
  Number of |
   Prenatal |
     Visits |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        122        1.22        1.22
          1 |         30        0.30        1.52
          2 |         73        0.73        2.25
          3 |         97        0.97        3.22
          4 |        135        1.35        4.57
          5 |        178        1.78        6.35
          6 |        278        2.78        9.13
          7 |        322        3.22       12.35
          8 |        467        4.67       17.02
          9 |        462        4.62       21.64
         10 |      1,419       14.19       35.83
         11 |        677        6.77       42.60
         12 |      1,921       19.21       61.81
         13 |        709        7.09       68.90
         14 |      1,075       10.75       79.65
         15 |        890        8.90       88.55
         16 |        491        4.91       93.46
         17 |        186        1.86       95.32
         18 |        167        1.67       96.99
         19 |         52        0.52       97.51
         20 |        121        1.21       98.72
         21 |         17        0.17       98.89
         22 |         18        0.18       99.07
         23 |         12        0.12       99.19
         24 |          6        0.06       99.25
         25 |         26        0.26       99.51
         26 |          3        0.03       99.54
         27 |          3        0.03       99.57
         28 |          5        0.05       99.62
         29 |          1        0.01       99.63
         30 |          6        0.06       99.69
         34 |          2        0.02       99.71
         35 |          2        0.02       99.73
         40 |          2        0.02       99.75
         48 |          1        0.01       99.76
         99 |         24        0.24      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015