Excitement over exchange-traded funds continues among financial advisors, according to a survey by the Journal of Financial Planning and the FPA Research and Practice Institute, a program of the Financial Planning Association.

ETFs are the preferred investment vehicle for 83 percent of the 283 financial advisors who took part in the 2016 Trends in Investing Survey released Tuesday. The popularity of ETFs—respondents chose them most frequently among 17 other options—has continued to grow since the survey started in 2006, when just 40 percent of advisors used or recommended ETFs.

The survey also indicated that 46 percent of advisors plan to increase their use or recommendation of ETFs with clients over the next 12 months. No other investment vehicle showed this level of anticipated increased usage, says the survey. Twenty-three percent plan to increase their use of individual stocks and 21 percent plan to increase their use of mutual fund wrap programs.

All of this comes at a time when some are questioning ETFsand their proliferation in recent years. Eric Balchunas says in Bloomberg the most recent ETFs—here have been 72 created this year—“either have an overly complex design or track a trendy, yet less substantive, theme.”

The survey shows advisors favor ETFs because of their lower costs (75 percent), tax efficiency (56 percent), trading flexibility (51 percent) and transparency of holdings (22 percent).

“The vast majority of ETFs are based on indexes, including those that focus on smart beta, and I think the growth in popularity is to a significant degree reflective of the ongoing shift among financial planners toward more passive approaches to investing client assets,” said Dave Yeske, practitioner editor of the Journal of Financial Planning. “Even planners who still use active investment strategies will often start with a core portfolio built around index funds, increasingly in the form of ETFs.”

“Although the concept of smart beta continues to get media attention and fund providers continue to release new ETFs products in this category, survey results indicate that only 24 percent of advisers have used smart beta ETFs with clients in the last 12 months,” an increase from 22 percent in 2015, the survey says.

The survey also found that advisors' long-term economic outlook is more positive than their short-term outlook. Sixty-four percent of advisors are optimistic about the economy over the next five years, but only 26 percent feel the same about the economic outlook for the next six months.