Concern wind power, which has been used for centuries to propel ships and mill grain. Modern wind power is obtained from windmills that convert wind energy into electricity. Figure 1.74 shows the annual percent growth in US wind power consumption between 2009 and 2014.

(a) According to the US Department of Energy, the US consumption of wind power was 721 trillion BTUs in 2009. How much wind power did the US consume in 2010? In 2011?

(b) Graph the points showing the annual US consumption of wind power, in trillion BTUs, for the years 2009 to 2014. Label the scales on the horizontal and vertical axes.

(c) Based on this data, in what year did the largest yearly increase, in trillion BTUs, in the US consumption of wind power occur? What was this increase? 

percent growth over previous year 30 20 10 2010 2012 2014 year