Frequencies for first 10,000 rows of injury72 variable in nhamcsed2015 dataset 

    Did the injury/trauma, |
    overdose/poisoning, or |
      adverse effect occur |
             within 72 hou |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
                     Blank |      7,628       76.28       76.28
                   Unknown |        110        1.10       77.38
                       Yes |      1,939       19.39       96.77
                        No |        297        2.97       99.74
Questionable injury status |         26        0.26      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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