Approximately 1.4 million adults in the United States identify as transgender, doubling previous estimates from leading researcher the Williams Institute, at the UCLA School of Law.

Their 2011 estimate put the adult transgender population in America at around 700,000, or 0.3 percent.

The new report, titled “How Many Adults Identify as Transgender in the United States,” is by researchers Andrew R. Flores, Jody L. Herman, Gary J. Gates and Taylor N. T. Brown.

They relied on data from the 2014 Behavioral Risk Factor Surveillance System (BRFSS), which includes representative surveys of the 50 states, the District of Columbia and US territories.

“In 2014, 19 states included a question about transgender identity on their BRFSS survey, and the number of states that ask that question is growing,” a press release said. “The authors used additional data from the U.S. Census Bureau’s American Community Survey to develop estimates of the transgender-identified adult populations of the other 31 states.”

“The findings from this study are critical to current policy discussions that impact transgender people,” said Jody Herman, one of the authors of the study. “Policy debates on access to bathrooms, discrimination, and a host of other issues should rely on the best available data to assess potential impacts, including how many people may be affected.”

The study revealed that Hawaii, California, Georgia and New Mexico have the highest percentage of adults identifying as transgender, at 0.8 percent. The states with the lowest reported adult transgender population, at 0.3%, are North Dakota, Iowa, Wyoming, Montana and South Dakota.

Younger adults are more likely to identify as transgender than their older counterparts.

The study found that among adults ages 18 to 24, 0.7% identify as transgender; ages 25 to 64, 0.6% identify as transgender; and ages 65 and older, 0.5% identify as transgender.