(Duluth, MN)  --  Numbers at the halfway point of the 2010 shipping season look good, with signs that demand for cargo on the Great Lakes will continue improving in the second half.  Cargo for U-S-flagged lakers is up 53-percent from last year and tonnage on the St. Lawrence Seaway is up 17-percent over the first half of 2010.  Duluth Seaway Port Authority Director Adolph Ojard (OH'-jard) says it reflects increases in the port of Duluth-Superior, adding almost all sectors of shipping are up in one fashion or another, but the strongest improvement has been iron ore.  Chuck Hilleran, an international shipping agent with Guthrie-Hubner in Duluth, says grain is showing an uptick and may increase more as the Russian wheat crop is stung by drought.