Frequencies for first 10,000 rows of optmtrc_srvc_cd variable in pos2010 dataset :

       SRV: |
 OPTOMETRIC |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,626       86.26       86.26
          0 |      1,224       12.24       98.50
          1 |         79        0.79       99.29
          2 |         60        0.60       99.89
          3 |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 17 May 2017