NCHS Dataline

National Center for Health Statistics (US). International Statistics Program: Training course on civil registration and vital statistics systems [cited 2015 Nov 30]. Available from: http://www.cdc.gov/nchs/isp/isp_fetp.htm.

Clarke TC Ward BW Freeman G Schiller JS . Early release of selected estimates based on data from the January–June 2015 National Health Interview Survey. Hyattsville (MD): National Center for Health Statistics; November 2015.

Centers for Disease Control and Prevention. NHANES 2013–2014 [cited 2015 Dec 2]. Available from: http://wwwn.cdc.gov/nchs/nhanes/search/nhanes13_14.aspx.