While sales slowed markedly in December, Sonoma County’s housing market in 2013 still posted its best year since 2006.

Buyers purchased more than $2.86 billion worth of houses and condominiums last year, according to The Press Democrat’s monthly housing report compiled by Pacific Union International Vice President Rick Laws. Total values increased 12 percent from 2012 and reached the highest level since 2006 when nearly $3.29 billion worth of homes were sold.

The sales value rose last year even though the number of purchases declined. The county recorded the sale of 4,971 single-family homes, a drop of 8 percent from 2012. Condo sales fell 11 percent to 662 properties.

Sales activity last year represented “the normalization of the market,” Laws said. Sales shrank dramatically for homes priced under $300,000 but increased 42 percent for properties priced above $400,000.

In contrast, he said, in the early years of the housing crisis, “all we were selling was the bottom of the market, primarily distressed sales.”

Looking forward, Laws said, plenty of buyers are seeking homes, but inventory remains low. December ended with 550 homes for sale, less than a two-months supply at the current pace.

The lack of available homes already is constraining sales, he said.

In December, buyers purchased just 335 single-family homes, the lowest amount for the month since 2007.

The median single-family home price last month was $465,000, an increase of 19 percent from a year earlier.

Sales activity was similar for the entire Bay Area.

Buyers purchased 6,714 houses and condos in December for the nine-county region, according to real estate information service Data Quick. Sales decreased 12.7 percent from a year earlier and were the lowest in six years.

The Bay Area median price last month for houses and condos was $548,500, an increase of 23.9 percent from a year earlier.

— Robert Digitale