Sales of existing homes in the Chicago area rose appreciably in December from the previous month but were still down almost 10 percent from their year-ago comparison, the Illinois Association of Realtors reported Thursday.

For the year though, thanks to a tax credit that helped sales during the first six months, Chicago-area sales of single-family homes and condos were down only 0.5 percent from 2009, to 69,010 homes sold last year. The median price of $185,000 in 2010 was a 5.6 percent drop from the previous year but the declines in median price varied widely across the area.

For instance, the median sales price fell only 2.2 percent in DuPage County last year but dropped 9.8 percent in Kane County. Cook County’s median price posted a 7.5 percent drop.

The realty trade group said 5,204 homes were sold in the Chicago area last month. That’s a 15.2 percent improvement from November but still down 9.9 percent from the 5,779 homes sold in December 2009, during one of the federal government’s tax-break programs for first-time homebuyers. The median sales price was $167,850 last month, compared with $182,000 in December 2009.

Within the city of Chicago, December condo sales plunged 19 percent in December from a year ago, to 1,005 units, but the median price decline moderated, declining 1.8 percent to $274,895. Single-family homes within the city saw a 17.3 percent sales decline, to 762 sales, while the median price increased 4.8 percent from a year ago, to $152,000.

For the year within the city, condo sales fell 2.5 percent, to 11,051 units sold at a median price of $267,900, down 4.3 percent. Sales of single-family homes and the median price were relatively flat, at 8,038 sales and a median selling price of $145,500.

“The recent income and corporate tax increases passed by the Illinois state legislature provide further complications for those trying to analyze the interaction between the economy and the housing market,” said economist Geoffrey J.D. Hewings, director of the Regional Economics Applications Laboratory of the University of Illinois in a statement.

“The picture is further complicated by the temporary upsurge in housing sales in the first quarter of 2010 that was fueled by the incentives to new and existing homeowners. These increases set the stage for an expected dampening in the annual sales growth data for 2011 for the first quarter.”