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

       SRV: |
 OBSTETRICS |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,626       86.26       86.26
          0 |        757        7.57       93.83
          1 |        557        5.57       99.40
          2 |         35        0.35       99.75
          3 |         25        0.25      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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