Frequencies for first 10,000 rows of spec variable in namcs1999 dataset :

  physician |
  specialty |      Freq.     Percent        Cum.
------------+-----------------------------------
         AI |         65        0.65        0.65
         CD |        513        5.13        5.78
        CHN |         55        0.55        6.33
        CHP |        158        1.58        7.91
        CTS |         18        0.18        8.09
          D |        833        8.33       16.42
        DIA |         25        0.25       16.67
         EM |         51        0.51       17.18
         FP |      1,518       15.18       32.36
         GE |        111        1.11       33.47
         GP |        211        2.11       35.58
         GS |        707        7.07       42.65
        GYN |         24        0.24       42.89
        HSO |         35        0.35       43.24
         ID |         17        0.17       43.41
         IM |        901        9.01       52.42
          N |        385        3.85       56.27
        NEP |         65        0.65       56.92
         NS |        113        1.13       58.05
        OBG |        440        4.40       62.45
         OM |         92        0.92       63.37
         ON |         47        0.47       63.84
        OPH |        681        6.81       70.65
        ORS |        379        3.79       74.44
         OS |         13        0.13       74.57
        OSM |         17        0.17       74.74
        OTO |        474        4.74       79.48
          P |        878        8.78       88.26
         PD |        480        4.80       93.06
        PDC |         18        0.18       93.24
        PHO |         28        0.28       93.52
         PM |        114        1.14       94.66
         PS |         55        0.55       95.21
        PUD |        108        1.08       96.29
          U |        354        3.54       99.83
         VS |         17        0.17      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016