10. Most common matching formula:

By far, sponsors' most common match formula is to contribute 50 percent of up to 6 percent of participant salary deferrals. About one-third of plans use that formula. Another 11.6 percent of plans match 100 percent of 6 percent deferrals; 7 percent of plans match 100 percent of 5 percent deferrals. (Photo: Fotolia)

1. Record savings rate:

The average pre-tax deferral rate was 8.3 percent, a record high in the annual report's 10-year history. Four in 10 participants increased their deferral rate last year. (Photo: Fotolia)

2. 6 percent auto-deferral leading the way:

In what may be the most significant data point in the survey, sponsors are now defaulting participants into plans at a 6 percent savings rate at record levels. Almost one-third of plans enroll savers at 6 percent, slightly more than the 32 percent that enroll at 3 percent. It's the first time the 6 percent deferral rate surpassed the 3 percent rate. (Photo: Shutterstock)

3. Roth contributions hit a 10-year high — though still low relative to traditional savings:

Almost 7 percent of participants made contributions to a Roth, or after-tax savings plan, a high in the report's history. Younger workers that tend to fall into lower tax brackets are driving utilization. Nearly one in 10 participants age 30 to 39 made a Roth contribution, as did 8.6 percent of participants age 20 to 29. Roth utilization increased among all age groups, suggesting that education around the option may be starting to take hold. (Photo: Getty)

4. Average account balance peaking:

The average account balance for all participants in 2017 was $92,402, up from $80,300 in 2015. Savers age 50 to 59 had an average balance of $152,579; savers age 60 to 64 had an average of $168,725. (Photo: Shutterstock)

5. TDFs account for most invested money:

Target-date funds account for the largest percentage of assets under management. In 2017, TDFs accounted for more than 41 percent of all assets. Equity funds accounted for about 35 percent. TDF investments surpassed stock investments in nearly every plan size category, with some exceptions in smaller plans.

6. Young workers driving TDF adoption rates:

Three-quarters of workers age 20 to 29 invest in a TDF. Investing in TDFs drops as workers get older. Only 38 percent of workers age 60 to 64 invest in a TDF; only 34 percent age 65 to 69 do. (Photo: Getty)

7. More workers going all in on TDFs:

Throughout the T. Rowe universe, 56 percent of participants have all of their savings in the funds, compared to 22 percent that are only partially invested in TDFs. Another 22 percent are not invested in a TDF. In 2013, only 46 percent of savers were fully invested in a TDF.

8. Sponsors continue to offer more investment options:

Sponsors have steadily increased the number of investment options over the past decade. Last year, plans averaged 16.2 options, compared to 13.6 in 2008. As participants have more options, they are consolidating their savings in fewer investments. On average, savings are spread between 2.5 investments. (Photo: Getty)

9. Catch-up contributions hit 10-year high:

More than 12 percent of savers made catch-up contributions when they were eligible; 11.3 percent of workers age 50 to 59 did so; 14 percent of workers age 60 to 64 did so. (Photo: Shutterstock)

10. Most common matching formula:

By far, sponsors' most common match formula is to contribute 50 percent of up to 6 percent of participant salary deferrals. About one-third of plans use that formula. Another 11.6 percent of plans match 100 percent of 6 percent deferrals; 7 percent of plans match 100 percent of 5 percent deferrals. (Photo: Fotolia)