A release from the Chamber of Marine Commerce is suggesting that there continues to be a high demand for road salt in the Great Lakes-Seaway region.  The St. Lawrence Seaway Management Corporation says salt shipments through the St. Lawrence Seaway were up 3 percent to 1.4 million metric tonnes between April 2 to July 31st. Other dry bulk categories such as cement are up 11 percent from last year — boosted by construction activity in the United States.  Gypsum shipments rose 35 percent and coke tonnage measured 657 thousand tonnes, up 23 percent compared to 2014.  Metallurgic coke is used for domestic steel production in Hamilton, Toledo and Burns Harbor, Indiana. But the corporation also reported a 7 percent drop in cargo tonnage across the board so far this year.  Declines in iron ore and coal shipments are to blame for the overall decrease.