Frequencies for first 10,000 rows of arrive variable in nhamcsed2005 dataset :

       mode of |
       arrival |      Freq.     Percent        Cum.
---------------+-----------------------------------
         blank |        331        3.31        3.31
     ambulance |      1,572       15.72       19.03
public service |        266        2.66       21.69
       walk-in |      7,604       76.04       97.73
       unknown |        227        2.27      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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