From a Port of Oakland news release:
Containerized import volume at the Port of Oakland in 2015 was essentially unchanged from 2014, according to statistics released today. The Port said imports declined just 0.2 percent after dropping nearly 40 percent last January and February.
Overall cargo volume decreased 4.9 percent in 2015, the Port said. It attributed the decline to an 11.5 percent drop in containerized exports. That was primarily the result of continued strength in the U.S. dollar, the Port said. The dollar’s relative value makes American goods more costly overseas.
http://www.portofoakland.com/newsroom/pressReleases/2016/pr_493.aspx