According to a new Vital Signs report published by the Centers for Disease Control and Prevention (CDC), the life expectancy of African-Americans from 1999 to 2015 has gone up, while the gap between white blacks and has gone down.

“The bottom line is that we are cautiously optimistic. However, stark disparities persist,” said Dr. Leandris Liburd,  associate director of the Office of Minority Health and Health Equity at the CDC during a press briefing.

Examining trends in mortality rates for the leading causes of death during 1999-2015, researchers concluded that the death rate among black Americans decreased from 1,135.7 to 851.9 per 100,000, a 25% fall while the disparity gap between blacks and whites went from 33% in 1999 to 16% in 2015.

It still remains that blacks are more likely to live four years less than whites with blacks younger than 65 having higher levels of self-reprted risk factors, chronic diseases and mortality from cardiovascular diseases and cancer.

While African-Americans older than 65 experienced the greatest improvement of all, with a 27 percent decrease in their death rate, the real concern comes with younger African Americans who are more likely to develop chronic disease and illness at a younger age than their white counterparts.

“Many younger African-Americans in their 20s, 30s and 40s are living and dying with chronic conditions that we more typically see in the older population,” says Timothy Cunningham, the CDC epidemiologist who led the report. “There’s still work to do.”

Researchers emphasized socioeconomic factors that contribute to this crisis. These include poverty, access to healthcare, education, and home ownership.

“Where we live determines our health; it determines our quality of housing, the schools we attend, our employment opportunities,” Cunningham said. “Individual behaviors are important, but one challenge we face is that we have to invest in the places where people live.”

Read the full report here.