Hawkeye Companys balance sheet reported, under the equity method, its long-term investment in Raven Company for comparative years as follows:

Investment in Raven Company stock (in millions): Dec. 31, 2015: $281 Dec. 31, 2014 : $264

In addition, the 2015 Hawkeye Company income statement disclosed equity earnings in the Raven Company investment as $25 million. Hawkeye Company neither purchased nor sold Raven Company stock during 2015. The fair value of the Raven Company stock investment on December 31, 2015, was $310 million.

Explain the change in Investment in Raven Company Stock from December 31, 2014, to December 31, 2015.