- Correspondence to Zachary Olson, School of Public Health, University of California, 276 Euclid Ave, Apt. 101, Oakland, CA 94610, USA USA;
- Received 14 April 2015
- Revised 21 July 2015
- Accepted 30 November 2015
- Published in print 1 August 2016.
- Published online 21 July 2016.
- Published first 4 January 2016.
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- Data supplement 1 - Online supplement
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