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

             is injury work related? |      Freq.     Percent        Cum.
-------------------------------------+-----------------------------------
                                 Yes |        205        2.05        2.05
                                  No |        247        2.47        4.52
                             Unknown |        643        6.43       10.95
Not applicable (not an injury visit) |      8,905       89.05      100.00
-------------------------------------+-----------------------------------
                               Total |     10,000      100.00

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