Frequencies for first 10,000 rows of injury variable in nhamcsed2015 dataset :

    Is visit related to an |
            injury/trauma, |
    overdose/poisoning, or |
       adverse effect of m |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
                     Blank |         16        0.16        0.16
                   Unknown |        400        4.00        4.16
                        No |      6,202       62.02       66.18
                       Yes |      3,356       33.56       99.74
Questionable injury status |         26        0.26      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Nov 2017