Amazon.com celebrated its 20th anniversary in July 2014. Its growth can be seen by examining its increasing sales volume (in $billions):

2008 ................................. 19.17
2009 ................................. 24.51
2010 ................................... 34.2
2011 ................................. 48.08
2012 ................................. 61.09
2013 ................................. 74.45
2014 ................................. 88.99

a. Construct a line plot for Amazon’s sales.

b. Describe the type of relationship that exists between the years in business and Amazon’s sales volume.