Data: U.S. Census Bureau; Chart: Axios VisualsHealth care expenses forced 8 million Americans into poverty in 2018, according to the Census Bureau. The big picture: That's actually an improvement from the past several years, when an annual average of 11 million people fell into poverty because of medical costs — a reflection of the country's expensive system.How it works: The Census Bureau tracks how various social programs and daily expenses influence poverty rates.Social Security, SNAP benefits and housing subsidies are among the most effective anti-poverty programs.But year after year, medical expenses remain "the largest contributor to increasing the number of individuals in poverty," according to the Census Bureau.Most people who have insurance and who make less than 150% of the federal poverty level don't have enough liquid assets to cover a $1,500 deductible.The bottom line: People who don't have insurance have the highest risk of falling into poverty, due to the high prices of drugs and procedures. But even working Americans who have coverage are facing bleaker financial futures because employers have shifted more health care costs onto their shoulders.Go deeper: Other developed countries limit out-of-pocket medical expenses