Frequencies for first 10,000 rows of prostrat variable in namcs1999 dataset :

   provider |
    stratum |
     marker |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,251       12.51       12.51
          2 |        816        8.16       20.67
          3 |        895        8.95       29.62
          4 |        483        4.83       34.45
          5 |        674        6.74       41.19
          6 |        464        4.64       45.83
          7 |        431        4.31       50.14
          8 |        510        5.10       55.24
          9 |        816        8.16       63.40
         10 |        354        3.54       66.94
         11 |        986        9.86       76.80
         12 |        415        4.15       80.95
         13 |        681        6.81       87.76
         14 |        493        4.93       92.69
         15 |        731        7.31      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016