Frequencies for first 10,000 rows of prov3810 variable in posclia2008 dataset :

  cert type |
   code # 1 |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        301        3.01        3.01
          1 |      1,123       11.23       14.24
          2 |      5,327       53.27       67.51
          3 |        811        8.11       75.62
          4 |      2,092       20.92       96.54
          9 |        346        3.46      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 26 Jan 2016