Vanguard, the giant defined-contribution asset manager, said Tuesday that more than two-thirds of workers auto-enrolled in a 401(k) are also automatically boosting their annual contribution rates.

That’s good news for anyone hoping for a secure retirement, it said, but automatic participation is specifically improving the retirement prospects of low-income, young and minority workers.

Jean Young, of Vanguard’s Center for Retirement Research, said nearly one-third (34 percent) of Vanguard plans had adopted automatic enrollment by the end of 2013, up from 24 percent five years earlier.

For employees enrolling in their first DC plan in 2013, 62 percent were automatically enrolled. Vanguard noted the overall participation rate in auto-enrollment programs is 82 percent, compared with 65 percent for employees voluntarily enrolled.

Sixty-nine percent who were auto-enrolled increase their contribution rates annually, but Vanguard suggests at too low of a default rate. Most of the plans that do automatically increase rates do so at 3 percent a year or lower. Vanguard recommends a typical enrollee contribute 12-15 percent of their income annually, including employer contributions.

Perhaps the best news from Vanguard was that the average participant account balance in Vanguard funds was $101,650 in 2013. Continuous participants — those who had 401(k) accounts in 2008 and stayed invested through 2013 — saw their balances rise by 182 percent in that period.

“Balances are now well ahead of the peak levels achieved prior to the global financial crisis. The effects of the market decline on retirement savings are now firmly in the past,” Young said.