Study the graph. A graph titled Renewable Energy Consumption by Source from 1949 to 2011 shows years on the x-axis, from 1950 to
2011, and Quadrillion B t u on the y-axis, from 0 to 4. The graph shows the usage for hydroelectric power, wood, biofuels, wind, and other. Hydroelectric power has the highest usage, and wind has the lowest usage. In what time period did hydroelectric power usage reach its peak? 1970–1980 1980–1990 1990–2000 2000–2010.
