U.S. oil prices closed above $60 a barrel on the final trading day of the year, the first time since mid-2015, as the commodity ended 2017 with a 12 percent gain spurred by strong demand and declining global inventories. International benchmark Brent crude futures ended the year with a 17 percent rise, supported by ongoing supply cuts by top producers OPEC and Russia as well as strong demand from China. The spread between the benchmarks widened throughout the year, as Brent responded to the drawdown in supply from major world producers while U.S. output continued to grow. The gains indicate that the global glut that has dogged the market since 2014 is shrinking. Earlier this year, oil prices slumped on concerns that rising crude production from Nigeria, Libya and elsewhere would undermine output cuts led by the Organization of the Petroleum Exporting Countries and Russia. […]