An improving economy and a low number of homes for sale boosted Orange County existing house prices 7.1 percent in the year ending in February, marking the second straight month of home price gains above 7 percent, according to the CoreLogic Home Price Index released Tuesday.

By comparison, the CoreLogic HPI showed O.C. price gains averaging 4.3 percent in 2015.

But the report conflicts with the trend shown in CoreLogic’s earlier home-price report for February. That report, based on a different methodology, showed the median price for an existing Orange County house was up a mere 3.4 percent.

The median is the price at the midpoint of all sales. The CoreLogic HPI focuses on percentage gains in house prices, determined by comparing individual home prices to the price of each dwelling’s previous sale. It only includes existing homes with a prior sale on record.

Elsewhere in the region, February’s house prices were up 7.6 percent in Los Angeles County and 6.6 percent in the Inland Empire counties of Riverside and San Bernardino, according to the CoreLogic HPI.

House prices were up 7.5 percent in California as a whole.

Nationally, CoreLogic reported a 6.8 percent price gain for February. Home prices rose in all 50 U.S. states, the Irvine-based real estate data firm reported.

Orange County has posted 45 consecutive months of year-over-year increases, although double-digit price jumps ended nearly two years ago, CoreLogic figures show.

In Los Angeles County, prices have been up for 46 straight months, and gains were posted for 47 months in the Inland Empire.

Nationally, prices have seen uninterrupted gains for four straight years, CoreLogic said.

U.S. home prices still are 6.5 percent below the April 2006 peak, the HPI shows, but are projected to reach a new peak in May 2017.

CoreLogic economists attributed higher appreciation rates to an improving economy and higher demand for a smaller supply of home-sale listings.

“Fixed-rate mortgage rates dropped more than one-quarter of a percentage point in the first three months of 2016, and job creation averaged 209,000 over the same period,” said CoreLogic Chief Economist Frank Nothaft. “These economic forces will sustain home purchases during the spring.”

The number of homes listed for sale is at its lowest level in three years, according to Steve Thomas’ ReportsOnHousing.com. That lack of inventory is boosting competition among homebuyers, which tends to drive sale prices higher.

For example, Orange County had an average of 5,455 homes posted in the Realtor-run multiple listing service in late March, the lowest for that period since 2013. Similar trends occurred in January and February.

Low inventory has plagued the Orange County housing market since 2012, and it’s getting worse in the lower ranges, Thomas said in his latest report.

In March of 2011, homes priced below $500,000 represented half of all listings, he reported. Last month, they represented 22 percent of listings and 33 percent of new escrows.

“What happened to affordable, entry level housing? The simple answer is appreciation,” Thomas’ report said. “The number of homes on the market in the low range is off by 16 percent and demand is off by 14 percent.”

Home price appreciation is expected to continue. Nothaft projected that U.S. prices will rise an average of 5.2 percent by next February.

Contact the writer: 714-796-7734 or jcollins@ocregister.com