Life expectancy in the United States has declined for the first time in more than two decades, according to a new report, a development linked to a range of worsening health problems in the country. US death rate increased 1.2 percent last year, the first time it has increased since 1993 and that led to a 0.1 percent drop in life expectancy, according to a report released Thursday by the National Center for Health Statistics. American males could expect to live 76.3 years at birth last year, down from 76.5 in 2014. Females could expect to live to 81.2 years, down from 81.3 the previous year, the report said. Rising fatalities from heart disease and stroke, cancer, diabetes, drug overdoses, accidents and other conditions caused the lower life expectancy. More than 2.7 million people died last year, about 45 percent of them from heart disease or cancer. “ I think we should be very concerned, ” said Anne Case, a Princeton University economist who u