Frequencies for first 10,000 rows of nprevis variable in natl1991 dataset :

      Total |
  Number of |
   Prenatal |
     Visits |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        158        1.58        1.58
          1 |         56        0.56        2.14
          2 |         98        0.98        3.12
          3 |        115        1.15        4.27
          4 |        185        1.85        6.12
          5 |        269        2.69        8.81
          6 |        401        4.01       12.82
          7 |        405        4.05       16.87
          8 |        620        6.20       23.07
          9 |        542        5.42       28.49
         10 |      1,444       14.44       42.93
         11 |        673        6.73       49.66
         12 |      2,030       20.30       69.96
         13 |        636        6.36       76.32
         14 |        655        6.55       82.87
         15 |        682        6.82       89.69
         16 |        324        3.24       92.93
         17 |        118        1.18       94.11
         18 |        102        1.02       95.13
         19 |         50        0.50       95.63
         20 |        211        2.11       97.74
         21 |         29        0.29       98.03
         22 |         21        0.21       98.24
         23 |         10        0.10       98.34
         24 |         15        0.15       98.49
         25 |         35        0.35       98.84
         26 |          6        0.06       98.90
         27 |          6        0.06       98.96
         28 |          4        0.04       99.00
         29 |          3        0.03       99.03
         30 |         24        0.24       99.27
         31 |          1        0.01       99.28
         32 |          1        0.01       99.29
         36 |          3        0.03       99.32
         38 |          2        0.02       99.34
         39 |          3        0.03       99.37
         40 |          2        0.02       99.39
         49 |          2        0.02       99.41
         99 |         59        0.59      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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