“Because of the investment losses stemming from the financial crisis, Social Security has become even more of a lifeline for many older Americans.

From 1999 to 2009, their incomes from financial assets fell by 25 percent to 50 percent, according to research by the Institute for Women’s Policy Research.

Some retirees have responded to their declining investments by working jobs to make up for their losses, an option the data show is much more difficult for those older than 75.

‘It’s a triple whammy,’ said Heidi Hartmann, the institute’s president. ‘The only thing out there is Social Security, your own earnings or, your kids’ earnings, frankly.’