Black Book’s Used Vehicle Retention Index for June showed how the impact from the spring market still left its mark even as summer began.

Editors released the June index reading on Tuesday, noting that it ticked up 0.6% from the previous month to land at 115.0.

Black Book explained the strong spring season continued into the first month of summer with a majority of segments strengthening in June. Editors pointed out full-size vans (up 1.43%) and premium sports cars (up 1.25%) performed exceptionally well.

“The uptick in the seasonally-adjusted index shows that the strength of the used vehicle values is steady,” Black Book executive vice president of operations Anil Goyal said in a news release.

“The strength is broadly seen across all mainstream vehicle segments, while luxury brand segments registered a decline,” Goyal continued.

The Black Book Used Vehicle Retention Index is calculated using the firm’s published wholesale average value on 2- to 6-year-old used vehicles, as a percent of original typically-equipped MSRP. It is weighted based on registration volume and adjusted for seasonality, vehicle age, mileage, and condition.

The index dates to January 2005 when Black Book published a benchmark index value of 100.0 for the market. During 2008, the index dropped by 14.1% while during 2016, the index fell by just 6.4%.

During 2011, the index rose strongly from 113.3 to 123.0 by the end of the year as the economy picked up steam and used vehicle values rose higher. It continued to remain relatively stable, rising slightly until May of 2014 when it hit a peak of 128.1.

To obtain a copy of the latest Black Book Used Vehicle Retention Index, go to this website.