Congestive heart failure was the No. 1 cause of hospitalizations among older Americans in 2004, new research shows.

Pneumonia was the second leading cause of hospitalizations among people 65 and older. Following that were hardening of the arteries, heart beat irregularities and heart attack, according to a report from the agency for Healthcare Research and Quality.

Seniors account for about 35% of hospital stays annually. By 2030, the number of Americans over 65 is expected to more than double to 71 million.