Global trade through the Port of Oakland totaled $21.29 billion in the first half of 2015. That placed Oakland 26th among the nation’s 450 top seaports, airports and border crossings, researchers at TradeNumbers reported. “The Port of Oakland conducts the most trade of any non-L.A. California port,” said the subscription trade publication. TradeNumbers said its analysis was based on U.S. Census Bureau data.       Oakland is the state’s third-busiest container seaport. Eight of the Port’s top 10 trading partners during the first half of 2015 were from Asia, TradeNumbers reported. No. 1 was China with trade valued at $6.8 billion. Perishables have been the leading containerized export by value shipped through Oakland so far this year, the publication said. They include nuts, meat and wine. Computers have been the highest-value import at Oakland. The value of total trade through Oakland declined 11.5 percent in the first half of 2015, TradeNumbers said. Labor-management disputes affected trade growth at most West Coast ports last winter. A strong dollar continues to inhibit exports by making U.S. goods more expensive overseas.