Scores of data points confirm that investors are ratcheting up their investment in exchange-traded funds (ETFs). When it comes to generational adoption of ETFs, Millennials are often credited with driving ETF growth, but other age brackets, including Generation X, get credit as well. However, a new report suggests that baby boomers trail three other generations when it comes to implementing ETFs into their portfolios.

"The 'BlackRock ETF Pulse Survey,' which polls advised and self-directed individual investors, found that only 27% of boomers invested in ETFs, compared to 42% of millennials (21-35) and 37% of Silvers (71+)," according to BlackRock, Inc. (BLK). BlackRock is the parent company of iShares, the world's largest ETF issuer. The survey says that Gen X ETF ownership is 29%, also above the level seen with baby boomers. Interestingly, millennials and Silvers, the parents of moomers, are adopting ETFs at a veracious pace. (See also: Are We in a Baby Boomer Retirement Crisis?)

Boomers' "children, and parents, however, are purchasing ETFs in record numbers. Millennials saw the biggest jump in ownership, with 42% compared to 33% last year," said BlackRock. "Silvers also had a strong uptick in ETF adoption, nearly doubling to 37% versus 22% last year. Usage among women increased to 30% from 23%."

Overall, ETF investment is on the rise. The BlackRock survey says that one in three investors now buy into ETFs, up from one in four in the previous survey. Nearly 90% of current ETF owners plan to continue or boost their investments in ETFs. "The number of investors set to buy ETFs in the next year spiked to 62%, from 52% last year, with millennials and Gen Xers (aged 36-51) leading the way (at 85% and 64%, respectively)," said BlackRock. (For more, see: Why ETFs Are a Smart Investment Choice for Millennials.)

Not surprisingly, costs remain a key reason why investors are flocking to ETFs. Last year, roughly three-quarters of ETF inflows were allocated to funds with expense ratios of 0.2% or less, and a significant percentage of those flows were directed to ETFs with fees of 0.1% or less.

"Other prominent uses include diversification, and international and sector exposures," according to BlackRock. "ETF investors are also thinking long term. One-third of investors plan to increase their use of ETFs for long-term investing, with the average holding period up to nearly six years, from five last year. Only 5% of investors use ETFs for less than a year." (For additional reading, check out: Millennials Love ETFs.)