Frequencies for first 10,000 rows of workrel variable in nhamcsed1995 dataset :

             is injury work related? |      Freq.     Percent        Cum.
-------------------------------------+-----------------------------------
Not applicable (not an injury visit) |      6,313       63.13       63.13
                                 Yes |        444        4.44       67.57
                                  No |      2,227       22.27       89.84
                             Unknown |      1,016       10.16      100.00
-------------------------------------+-----------------------------------
                               Total |     10,000      100.00

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