We define x as a year between 2008 and 2013 and y as the total number of smartphones sold that year, in
millions. The table shows values of x and corresponding y
values.

Year ( x ) and number of smartphones in millions ( y )
2008 – 3.7
2009 – 17.3
2010 – 42.2
2011 – 90
2012 – 125
2013 – 153.2

In which year were 90 million smartphones sold?