Frequencies for first 10,000 rows of prov3810 variable in posclia2010 dataset :

  cert type |
   code # 1 |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        282        2.82        2.82
          1 |      1,137       11.37       14.19
          2 |      5,420       54.20       68.39
          3 |        796        7.96       76.35
          4 |      2,028       20.28       96.63
          9 |        337        3.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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