Here in Iowa, where wind energy alone provides more than one-third of the power supply, it may not sound that impressive that 18.3 percent of the nation’s installed capacity is from renewable energy sources. But the federal government’s 2016 Renewable Energy Data Book shows the renewable industry is growing across the country. Among the tidbits: Renewable energy accounted for 67 percent of U.S. electricity capacity additions in 2016, up from 64 percent in 2015.