Life expectancy in the US is continuing to drop because of accidental deaths from the prescription and illicit opioids that are sweeping the country. This is the second year in a row that life expectancy declines in the US — to 78.6 years in 2016, down from 78.7 years in 2015 and 78.8 in 2014, according to a report by the National Center for Health Statistics (NCHS).

The leading causes of death in the US are still heart disease and cancer. But the opioid epidemic is taking a heavy toll — particularly on young and middle-aged Americans. Last year, over 63,000 people died of drug overdoses, a 21 percent increase from 2015. The last time life expectancy dropped for two years in a row was in 1962 and 1963, when a particularly bad flu season caused lots of deaths, according to the Washington Post.

How long people can expect to live in a certain country is a sign of how healthy the overall population is; it’s also considered a measure of quality of life. Advances in medicine and sanitation have boosted life expectancy around the world, especially in Africa. But compared to other developed nations, the United States is now an outlier.

In 2015, a study found that death rates in the US were rising for middle-aged white Americans because of suicide, drugs, and alcohol abuse. A study published in JAMA in September showed that from 1970 to 2000, life expectancy in the US rose by about 2.5 months every year, then slowed starting in 2000, and stopped altogether in 2014. That’s because deaths from drug overdoses skyrocketed: In 2000, more than 17,000 people died of drug overdoses. Today, that number has almost quadrupled. The latest data from the NCHS shows that, as a result of the opioid epidemic, death rates increased for younger age groups and decreased for older people since 2015. Life expectancy for women stayed the same, at 81.1 years (vs. 76.1 years for men).

In October, President Donald Trump declared the opioid crisis a public health emergency — a move intended to expand access to treatment and loosen regulations to fight the epidemic. But the declaration was criticized for not unlocking significant new funding experts say are needed to solve the opioid crisis.