Frequencies for first 10,000 rows of nprevis variable in natl1986 dataset :

      Total |
  Number of |
   Prenatal |
     Visits |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        214        2.14        2.14
          1 |         99        0.99        3.13
          2 |        145        1.45        4.58
          3 |        206        2.06        6.64
          4 |        241        2.41        9.05
          5 |        295        2.95       12.00
          6 |        409        4.09       16.09
          7 |        419        4.19       20.28
          8 |        598        5.98       26.26
          9 |        677        6.77       33.03
         10 |      1,186       11.86       44.89
         11 |        748        7.48       52.37
         12 |      1,682       16.82       69.19
         13 |        736        7.36       76.55
         14 |        827        8.27       84.82
         15 |        684        6.84       91.66
         16 |        241        2.41       94.07
         17 |        109        1.09       95.16
         18 |        103        1.03       96.19
         19 |         30        0.30       96.49
         20 |        111        1.11       97.60
         21 |         19        0.19       97.79
         22 |         19        0.19       97.98
         23 |          8        0.08       98.06
         24 |         13        0.13       98.19
         25 |         25        0.25       98.44
         26 |          4        0.04       98.48
         30 |          5        0.05       98.53
         35 |          1        0.01       98.54
         36 |          2        0.02       98.56
         37 |          1        0.01       98.57
         42 |          1        0.01       98.58
         99 |        142        1.42      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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