Defined benefit pension plans have consistently earned higher rates of return than defined contribution plans — predominately 401(k) plans, according to an analysis released Wednesday.

From 1995 through 2011, the median annual rate of return for defined benefit plans was 8% compared with about 7.3% for defined contribution plans, according to the Towers Watson & Co. analysis.

“DB plans have some inherent advantages that have helped them historically outperform their 401(k) counterparts, such as lower investment fees, longer investment time horizons and management by investment experts,” Dave Suchsland, a senior retirement consultant in Towers Watson's Philadelphia office, said in a statement.

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In 2011, the most recent year for which information is available, the difference in rates of return for defined benefit and defined contribution plans was especially sharp.

In 2011, the median rate of return for defined benefit plans was 2.7%. By contrast, defined contribution plans had a negative rate of return of 0.2%. That nearly three-point point difference in median rates of return was the widest margin since 1995, the first year of the Towers Watson analysis of rates of return for the two types of plans.

That difference in 2011 investment performance may have been aided by defined benefit plan sponsors shifting more plan assets from equities to long-duration bonds, Towers Watson said.

“That move proved to be successful from a total investment return perspective, as the performance of long-duration bonds far outpaced that of equity markets during 2011,” Towers Watson said.

In all, median rates of return for defined benefit plans were higher than defined contribution plans in 13 of the 17 years Towers Watson analyzed.

The highest rate of return for defined benefit plans during those 17 years was in 2003, when the plans had a median rate of return of 21% vs. a median rate of return of 19.6% for defined contribution plans.

The best year for defined contribution plans was 2009, with a median rate of return of 20.9% vs. 15.5% for defined benefit plans.

The worst year for both defined benefit and defined contribution plans was 2008, the year in which the equities' markets plunged as the Great Recession deepened. In 2008, defined benefit plans had a median negative rate of return of 23.4%, while defined contribution plans dropped 26.1%.

The number of plans in the analysis ranged from a low of 1,472 in 1999 and a high of 3,063 in 1995. In 2011, 2,080 plans were analyzed.