For this end-of-year post leading into 2018, I choose to address the big topic of how long we live in America, and what underpins the sobering fact that life expectancy is falling.

Life expectancy in the United States declined to 78.6 years in 2016, placing America at number 37 on the list of 137 countries the World Economic Forum (WEF) has ranked in their annual Global Competitiveness Report 2017-2018. Americans’ life expectancy falls far below that for the health citizens of Australia, France, Canada, Finland, and the UK. While Australians’ and Britons’ life expectancies declined from 2015-16, their outcomes are still several years greater, at 72.5 for the Aussies (#10) and 81.6 for the Brits (#20).

As the chart shows, the U.S. falls between #36, Qatar, and #38, Poland, in this analysis, below lower-income nations like South Korea (#12), Malta (#16), Chile (#18), and Slovenia (#29).

The WEF report talks about countries’ abilities to do business and mashes up dozens of data points, well beyond life expectancy. The Global Competitive Index is made up of factors covering institutions, infrastructure, macroeconomics, health and primary education, higher education and training, goods market efficiency, labor market efficiency, financial market development, technological readiness, market size, and innovation.

Most of the data points underneath these pillars are social determinants of health: beyond health and primary education, macroeconomics set the context for health citizens’ financial wellness, job and income security. Infrastructure can bolster or diminish public health through clean (or dirty) water, clean (or dirty) air, safe and healthy physical built environments, and accessible and active transportation networks.

The U.S. performance on these basic requirements improved at the margin in 2016. However, the macroeconomic environment scored a very low 83 out of the 137 world nations. Thinking about the WEF “fine print” on basic requirements can help us understand what underlies declining life expectancy in the United States of America. Most of the media coverage of this statistic has been focused on the impact of the opioid epidemic in the U.S. A few others, rightly, point to obesity and the risk factors for non-communicable disease.

The U.S. is hardly “united” in this statistic: for people who live longer, it helps to be born and raised in a wealthier zip code, have access to better education and healthy food sources. A Lancet article published earlier this year, Inequality and the health-care system in the USA, noted that “widening economic inequality in the USA has been accompanied by increasing disparities in health outcomes.”