Funding for this research was provided by:
National Center for Injury Prevention and Control (R49 CE002096)
Received: 20 February 2019
Accepted: 1 April 2019
First Online: 20 May 2019
Ethics approval and consent to participate
: Ethics approval was not needed for this work because it was based on publicly available data and because it did not involve human subjects research.
: Not applicable.
: Dr. Guohua Li serves as editor-in-chief of the journal, Injury Epidemiology, and was not involved in the review or handling of this manuscript.
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