Frequencies for first 10,000 rows of mdcl_schl_afltn_cd variable in pos2018 dataset :

    Medical |
     School |
Affiliation |
       Code |      Freq.     Percent        Cum.
------------+-----------------------------------
          . |      8,562       85.62       85.62
          1 |         78        0.78       86.40
          2 |        123        1.23       87.63
          3 |         41        0.41       88.04
          4 |      1,196       11.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Feb 2019