Frequencies for first 10,000 rows of prov3810 variable in posclia2006 dataset :

  cert type |
   code # 1 |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        322        3.22        3.22
          1 |      1,141       11.41       14.63
          2 |      5,221       52.21       66.84
          3 |        784        7.84       74.68
          4 |      2,163       21.63       96.31
          9 |        369        3.69      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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