WASHINGTON (June 17)—Natural rubber prices are reaching their highest levels in the past few years. Standard Indonesian Rubber 20 delivered to Norfolk, Va., or New Orleans reached 42½ cents per pound June 14, a 50-percent increase from the beginning of the year. Two major Thai rubber producing companies defaulting on their contracts are a major factor behind the increase. "If Thai production is lacking, you can always turn to Indonesia or Malaysia," said Lou Mucciolo, president of the Rubber Trade Association of America. "Then as the market got some major momentum behind it, there was some purchasing beyond shortcomings. Each day a little more momentum builds."