Funding for this research was provided by:
Bill and Melinda Gates Foundation
Received: 1 May 2017
Revised: 2 June 2017
Accepted: 13 June 2017
First Online: 3 August 2017
Compliance with ethical standards
: The authors of this paper have complied with all ethical standards and do not have any conflicts of interest to disclose at the time of submission.
: The study did not involve human participants and/or animals; therefore, no informed consent was needed.
: The funding source played no role in the design of the study, the analysis and interpretation of data, and the writing of the paper. GBD 2015 is funded by Bill & Melinda Gates Foundation.