Frequencies for first 10,000 rows of prov0830 variable in pos1991 dataset :

        lab |
directors - |
 doctorates |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,878       98.78       98.78
          1 |        107        1.07       99.85
          2 |         11        0.11       99.96
          3 |          2        0.02       99.98
          4 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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