A German government debt auction drew some of the weakest demand since the introduction of the euro, signaling diminishing investor appetite for even the safest euro-zone assets amid Europe’s worsening debt crisis….The German government was able to sell only €3.644 billion $4.92 billion of the €6 billion in 10-year bunds on auction for an average yield of 1.98%. Interest rates on Germany’s 10-year bonds rose sharply after the auction to 2.09%, their highest level in three weeks, leapfrogging the yield on the U.S. 10-year note.