Hawaii’s population is projected in a state economic report to increase gradually and reach 1.65 million people by 2045, with the fastest growth occurring on the neighbor islands.

The elderly population, defined as those age 65 and older, will account for nearly a quarter, or 23.8 percent, of the population compared with 17.1 percent in 2016, according to the report released Thursday by the state Department of Business, Economic Development and Tourism.

The report, “Population and Economic Projections for the State of Hawaii to 2045,” predicts that the resident population will grow at 0.7 percent per year between 2016 and 2025 and then drop to a 0.5 percent annual growth between 2025 and 2035. During the last decade covered by the report, the state population is seen growing at just 0.3 percent a year.

DBEDT’s report, the ninth in a series of long-range projections dating back to 1978, helps the state and counties with infrastructure and economic planning, and provides businesses with projections they can use to develop their growth strategies, according to DBEDT Director Luis Salaveria.

Neighbor island counties are expected to grow the fastest during the three-­decade period and leave Hono­lulu County with 65.1 percent of the total state population in 2045, down from 69.5 percent in 2016. The elderly population of 65 and over will increase at an annual rate of 1.7 percent between 2016 and 2045, with those 85 and over to grow at an annual rate of 3.6 percent, according to the report.

By 2045 Honolulu County’s population is expected to be nearly 1.1 million, followed by Hawaii County at 273,200, Maui County at 211,500 and Kauai County at 90,000. DBEDT also projected that females will live nearly five years longer than males and that the life expectancy at birth for a female in Hawaii will be 88.5 years in 2045 compared with 83.8 years for a male. Those numbers are up from 84.4 years and 78.7 years, respectively, in 2014, according to DBEDT estimates.

“The world changes rapidly with new technology and regulations, so it is difficult to project the economic indicators precisely into the future,” DBEDT Chief Economist Eugene Tian said in a news release accompanying the report. “We conduct this long range forecast every five to six years. We also conduct short-term economic forecasts every quarter of the year.”

In DBEDT’s 2040 projection series, which was released in 2012, the state agency projected Hawaii’s resident population would be 1,418,250 in 2015. The actual estimate for the same year by the U.S. Census Bureau was 1,425,157.

“(That’s) a difference of 6,907 people or a 0.5 percent forecasting error for that year,” Tian said.

DBEDT’s new report also forecast that Hawaii’s real, or inflation-adjusted, gross domestic product would grow at a pace of 1.7 percent a year between 2016 and 2045. GDP, which is the best way to measure a state or country’s growth, tracks the total value of all goods and services produced within a given time period.

In other areas, DBEDT forecasts that from 2016 to 2045 civilian jobs will rise at an 0.8 percent annual rate, and visitor arrivals by air during that period will increase at an annual rate of 1.1 percent to 12.2 million in 2045.