Frequencies for first 10,000 rows of workrel variable in nhamcsopd1995 dataset :

             is injury work related? |      Freq.     Percent        Cum.
-------------------------------------+-----------------------------------
Not applicable (not an injury visit) |      8,992       89.92       89.92
                                 Yes |        131        1.31       91.23
                                  No |        271        2.71       93.94
                             Unknown |        606        6.06      100.00
-------------------------------------+-----------------------------------
                               Total |     10,000      100.00

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