Los Angeles County and the Inland Empire posted some of the nation’s steepest rent increases during the fourth quarter of 2016, according to figures released this week.

Axiometrics, a research firm that tracks apartment development and rental trends, showed that L.A. County was tied with the Las Vegas-Henderson-Paradise, Nevada region for the biggest quarterly increase in rental prices among the top 25 U.S. markets. The county’s average monthly rent increased 0.6 percent during the fourth quarter to $2,260.

The Inland Empire ranked seventh on the list with a 0.1 percent increase that bumped its average monthly rent up to $1,485.

The two-county region posted the second largest year-over-year increase, however. The average monthly rent for an apartment in the Inland Empire rose 6.6 percent from the fourth quarter of 2015. L.A. County ranked 18th on the list with an annual increase of 3.9 percent.

Axiometrics’ report shows that the national apartment market continued to perform above its long-term average in the fourth quarter of 2016 although seasonal changes and continued declines in major markets contributed to the lowest annual rent growth in 6½ years.

The average rent nationwide was $1,277 per a month in the fourth quarter of this year compared to $1,245 in the fourth quarter of 2015. That equated to a year-over-year increase of 2.3 percent for the fourth quarter of 2016, more than 2 percentage points below the 4.6 percent annual rental growth of a year ago. It also marked the fifth straight quarter in which the annual growth rate of rents decreased.

But rental growth is still above the long-term average of 2.2 percent, according to Jay Denton, Axiometrics’ senior vice president of analytics.

“Though the market has moderated, it’s important to stress that we’ve seen a very strong market for more than six years,” Denton said in a statement. “Axiometrics had predicted this moderation since the market could not sustain the peak of 2014 and 2015. Now we’re forecasting that, although rent growth may fall below the long-term average for periods in 2017, it will remain positive with a rebound expected in 2018 and 2019.”

Bill Podley, chairman of Podley Properties in Pasadena, said Southern California’s rental market is challenging.

“There is upward pressure for more apartments,” he said. “Our population is increasing and our supply of new multi-family housing is not keeping up.”

A number of new apartment communities are planned or have been built in Pasadena, Podley said, but many of the units are too pricey for potential renters.

“Some of these apartments are renting for $2,000 to $3,000 a month,” he said. “They are not designed for someone who earns $3,000 a month, so service workers and police and firemen often can’t afford to live in the community where they work.”

Earlier this year, ApartmentList.com reported that Pasadena had the biggest year-over-year rent increase in the Los Angeles metro area — a bump of 8 percent between July 2015 and July of this year. The median monthly rent — the point at which half of the rents are higher and half are lower — for a two bedroom apartment in Pasadena went for $2,640 at that time.

But other rents were far higher.

Pacific Palisades posted the most expensive rent for July, where the median price for a two-bedroom rental went for $4,580 a month. Venice was close behind at $4,500, and Brentwood, Westwood and Century City were all priced at $4,000 or more per month.

Another analysis released earlier this month from ApartmentList.com showed that more than half of the Southern California households that rent are financially strapped. That means they are spending more than 30 percent of their income on housing and may have difficulty affording necessities like food, clothing, transportation and medical care.