LAWRENCEVILLE, Ga. -

Used prices were falling in December, and with an influx of off-lease vehicles expected to hit the lanes this year, declines as 2015 wrapped up were just the beginning.

And with new auto sales reaching record levels for 2015 — almost 17.5 million — it seems growing used supply with continue to spur depreciation in the coming years.

According to Black Book data, trucks finished the year with a total depreciation rate of 9.2 percent, ending the year with an average price of $20,543.

Cars dropped by a significantly more dramatic 18.2 percent to end 2015 with an average price of $14,196.

Truck sales soared in 2015 amid unusually low gas prices, and demand served to strengthen prices in the auction lanes.

With the increase in overall supply expected to start impacting the market this year, Black Book predicts 2016 deprecation to come in at close to 14 percent.

Prices were still on the way down in December, as well.

According to Black Book, the average price of a used vehicle for model years 2010-2014 fell by 1.8 percent in December.

Cars took a bigger 2-percent hit, while truck prices fell by 1.7 percent.

“Entering 2016, a record year for car sales totaling more than 17 million vehicles, the decrease in used car prices that we are seeing are showing a still-stable used-vehicle market,” said Anil Goyal, vice president of automotive valuation and analytics for Black Book. “One thing to watch, however, is the discrepancy in depreciation patterns between car and truck segments, as this gap is widening.”

Subcompact luxury CUVs took the biggest depreciation hit out of all the segments. Prices for this segment dropped 6 percent in December. After the drop, the segment started 2016 with an average price of $18,039, which is down 20 percent year-over-year.

Black Book pointed out three other segments saw monthly depreciation rates of 3.2 percent or more.

The subcompact luxury CUVs (down by 6 percent), sub-compact crossovers (down by 3.3 percent) and the compact vans (down 5.3 percent) all saw larger-than-average price drops.

Like was seen much of the year, full-size pickups once again posted the lowest depreciation rate in December, with rates only dropping by 0.5 percent. Vehicles in this segment started the year out with an average price of $23,379, which is down 1.7 percent year-over-year.