WASHINGTON (AP) — Interest rates on short-term Treasury bills rose in Monday's auction with rates on six-month bills climbing to their highest level in nine years. The Treasury Department auctioned $42 billion in three-month bills at a discount rate of 1.105 percent, up from 1.090 percent last week. Another $36 billion in six-month bills was auctioned at a discount rate of 1.245 percent, up from 1.240 percent last week. The three-month rate was the highest since those bills averaged 1.180 percent on July 24.