WEDNESDAY, Jan. 11 (HealthDay News) -- Americans are living longer, a new report shows, with the average life expectancy going from 78.6 years in 2009 to 78.7 years in 2010.

Meanwhile, U.S. death rates dropped half a percent between 2009 and 2010, and hit the lowest rate ever, at 746.2 deaths per 100,000 people, according to the latest set of data from the U.S. Centers for Disease Control and Prevention's National Center for Health Statistics.

And while both heart disease and cancer stubbornly remain in place as the nation's leading killers (together accounting for 47 percent of deaths in 2010), death rates here declined as well. Mortality from heart disease went down 2.4 percent, while it dropped 0.6 percent for cancer.

The report is based on 98 percent of death certificates from 50 states and the District of Columbia available to the NCHS.

"In many regards, I think the health of the nation is improving and people are living to an older age so that's good news," said Dr. David McClellan, acting regional chair of family and community medicine at Texas A&M Health Science Center College of Medicine. "But we are starting to see age-related diseases have more prominence."

For instance, pneumonitis (aspiration pneumonia) often happens when people get old enough and debilitated enough to where they can't swallow. This could be due to dementia or as the aftermath of a stroke, he explained.

There's also "a long way to go in terms of combating the epidemic of smoking, obesity, poor diet and exercise," he said. "If we could get the smoking epidemic under control, we'd probably see the numbers improve even more."

Another expert was more optimistic.

"This is good news. We're making major progression in cancer and heart disease through decreases in smoking," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La.

Statins are also playing a part in reducing the death toll from heart disease, while cancer screening is also helping to save lives, Brooks added.

There were slight shuffles in the rankings of other causes of death.

Homicide fell out of the top 15 category for the first time since 1965, replaced by pneumonitis.

Kidney disease and pneumonia/influenza switched places, with the former now 8th and the latter now 9th.

"Pneumonia and influenza have really dropped a lot. Several years ago, they were the sixth leading cause of death," said Dr. Michael Niederman, chairman of medicine at Winthrop University Hospital in Mineola, N.Y. "To me, this is very encouraging because we're dealing with older populations where many patients frequently have pneumonia, but this affirms the national priority on immunization, both influenza and pneumococcal."

The other leading causes of death (in order) were: chronic lower respiratory diseases, cerebrovascular disease (stroke), accidents, Alzheimer's disease, diabetes, kidney disease, suicide, septicemia, liver disease, hypertension and Parkinson's.

Many of these are clearly diseases related to the aging population, Brooks noted.

Death rates also declined for influenza and pneumonia (by 8.5 percent), septicemia (3.6 percent), stroke (1.5 percent), respiratory diseases (1.4 percent) and accidents (1.1 percent).

Meanwhile, death rates increased for five of the top 15: Parkinson's disease (4.6 percent), pneumonitis (4.1 percent), liver disease and cirrhosis (3.3 percent), Alzheimer's disease (3.3 percent) and kidney disease (1.3 percent).

The death rate for HIV/AIDS (which was not among the 15 leading causes of death) declined 13.3 percent between 2009 and 2010. But the virus remains a significant concern, especially for people aged 15 through 64.

There was also good news in infant mortality, with rates in 2010 down 3.9 percent from 2009.

But Dr. Suzanne Steinbaum, a preventive cardiologist with Lenox Hill Hospital in New York City cautioned against getting too excited over the findings.

"This is good news. I don't think it's great news," she said. "With the increased incidence in obesity, diabetes, high blood pressure, high cholesterol, we're going to start seeing people getting sicker younger."

More information

Visit the U.S. National Center for Health Statistics for more information on the health of Americans.