Hawaii has the fourth-highest number of millionaires per capita in the U.S., according to a new study.

The Phoenix Global Wealth Monitor released Wednesday shows that stable economic growth helped Hawaii maintain its ranking, according to lead researcher David Thompson.

The report’s data show that of 473,750 total households in Hawaii, 32,829 or 6.93 percent have $1 million or more in investable assets, which is defined as liquid wealth excluding real estate, employer-sponsored retirement plans and similar assets.

Maryland tops the ranking with 7.67 percent of households occupied by millionaires.

Second-ranked Connecticut’s millionaire count is at 7.23 percent, and third-ranked New Jersey’s is 7.14 percent.

Alaska’s millionaire count per capita trails Hawaii slightly at 6.82 percent.

Hawaii topped the nation in 2010, with 6.93 percent of households having investable assets of $1 million or more, but it dipped to second place in 2011 and 2012, with Maryland taking the lead.

According to researchers, Hawaii’s per-capita millionaire count peaked at 7.29 percent in 2012, when Maryland’s was at 7.31.

Thanks to the oil boom, North Dakota moved to No. 20 in 2014 from 29 in 2013. Its neighbor South Dakota was the biggest gainer this year, rising 12 places to No. 26.

"The amazing rise of North Dakota in the millionaires rankings clearly demonstrates the power of an industry to quickly create wealth," said David Thompson, managing director of the Phoenix Global Wealth Monitor. "However, the states that are consistently in the top 10 have much more diversified economies."

Thompson said it will be challenging for North Dakota to maintain its rise in the rankings once the oil boom subsides.