When saving for retirement is cheap and easy to do, more Americans will do it. That’s been the premise of recent innovations by the Vanguard Group, and the Malvern-based investment pioneer just announced that is precisely what’s been happening.

Vanguard released its annual report of defined retirement contributions, How America Saves 2015, just last week.

“The first step in retirement savings is participation,” lead author and Vanguard Center for Retirement Research Senior Research Analyst Jean Young said. “Over the past decade, we’ve seen a meaningful jump in total participation rates. Three-quarters of eligible workers now participate in their employer’s plan, up from two-thirds 10 years ago, underscoring the impact of autopilot plan designs.”

That’s because Vanguard has championed the autopilot concept, getting its plan sponsors to help make participating in retirement savings a default option for employees.

It has also simplified an employee’s selection of an investment portfolio through target-date funds that pre-determine age- and risk-appropriate portfolios based on when the employee plans to retire. Now up to $4 of every $10 deposited in a Vanguard plan goes into a target-date fund.

Investors are becoming more diversified and balanced, too, with the help of Vanguard’s signature low-cost index funds — 82 percent of retirement investors held equity index investments at the end of last year.

One of the biggest remaining challenges is getting employees to contribute more to their retirement.

“About half of participants in Vanguard-administered defined contribution plans are saving 10 percent or more,” Young said.

Many of the others are still at the minimal default rates — 3 percent or less — offered by the autopilot enrollment.

“We share with our sponsor clients an obligation to move the dial on savings rates and give participants the best chance for investment success,” Vanguard Institutional Investor Group Managing Director Martha King said.

Read more highlights from the study on Vanguard’s website here.