Giving from private foundations, federal agencies, and corporations has quadrupled the amount spent in the past two decades to improve global health, according to a study by the University of Washington, reports The Seattle Times. Some $22-billion is now poured into such efforts.

The Bill & Melinda Gates Foundation, in particular — which helped establish a University of Washington institute to measure global health spending with a $105-million grant — has had a profound influence on global health support, said the researchers.

Yet imbalances remain in how and where the money is directed, the researchers said. The countries with the greatest needs aren’t always getting the most aid, and the largest amount of money has gone to HIV/AIDS programs. In 2007, $5.1-billion was devoted to HIV/AIDS, and slightly less than $1-billion was spent to strengthen health systems in developing countries.