Frequencies for first 10,000 rows of prostrat variable in namcs1996 dataset :

   provider |
    stratum |
     marker |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,502       15.02       15.02
          2 |      1,035       10.35       25.37
          3 |      1,392       13.92       39.29
          4 |        830        8.30       47.59
          5 |        486        4.86       52.45
          6 |        415        4.15       56.60
          7 |        439        4.39       60.99
          8 |        553        5.53       66.52
          9 |        700        7.00       73.52
         10 |        245        2.45       75.97
         11 |        410        4.10       80.07
         12 |        373        3.73       83.80
         13 |        362        3.62       87.42
         14 |        375        3.75       91.17
         15 |        883        8.83      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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