On February 6, 2011, the United States dollar was worth 508.11 colones. The colón has had an unusual relationship with the U.S. dollar that may best be described as a "crawling peg"; instead of being defined by a constant value to the dollar, the colón instead would grow progressively weaker at a fixed rate of about 3.294 colones per dollar per month. On October 16, 2006, however, this crawling peg was modified due to weakness in the U.S. dollar and the perception that the colón is now undervalued. The exchange rate is now free to float within a currency band referenced to the United States dollar. The floor of the band has been set at a fixed value, while the ceiling changes at a fixed rate. In practice the exchange rate has remained fixed at the lower value of the currency band.