Frequencies for first 10,000 rows of nprev12 variable in natl1988 dataset :

  Number of |
   Prenatal |
     Visits |
     Recode |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        206        2.06        2.06
          2 |        178        1.78        3.84
          3 |        382        3.82        7.66
          4 |        617        6.17       13.83
          5 |        931        9.31       23.14
          6 |      1,747       17.47       40.61
          7 |      2,525       25.25       65.86
          8 |      1,621       16.21       82.07
          9 |        924        9.24       91.31
         10 |        259        2.59       93.90
         11 |        290        2.90       96.80
         12 |        320        3.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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