More than one-third of participants in Vanguard 401(k) plans invested in a professionally managed account in 2012, the company said Tuesday.

According to Vanguard’s latest report on its customers’ habits, “How America Saves 2013,” 27 percent of all participants in its plans were invested in a single target-date fund in 2012. Another 6 percent held a single traditional balanced fund, and 3 percent used a managed account advisory program.

The number of individuals who chose a professionally managed option more than doubled to 17 percent since 2007. Also, more participants took advantage of investment advice offered by Vanguard in 2012, rising to 14 percent.

Account balances, although not the primary indicator of retirement readiness, rose by 10 percent to $86,212 in 2012. The increase reflected ongoing contributions and a robust stock market.

One-fifth of investors saved at least 10 percent in their retirement accounts in 2012 and 11 percent saved the maximum allowed. Fifteen percent of participants over the age of 50 made catch-up contributions. Including employee and employer contributions, the average total savings rate in 2012 was 10.5 percent.

The average participant deferral rate was 7 percent in 2012, down slightly from its peak of 7.3 percent in 2007. Part of the problem is that default contribution rates set by many plans that use automatic enrollment are too low. Many times, the default investment rate is 3 percent of pay or lower, which experts say is not high enough.

“While we are seeing good news overall in the retirement planning habits of participants, many Americans are still not saving enough for the future,” said Jean Young, one of the authors of the Vanguard report. “Simply put, people need to save more and save more now.”

Vanguard, headquartered in Valley Forge, Pa., is one of the world’s largest investment management companies with more than $2.2 trillion in U.S. mutual fund assets under management.