The data shows a parabolic trend. In fact, we can see that the selling were good in 2007, started to decrease untile they reached a minimum in 2009, and from there they started growing again. This high - low - high (or viceversa) behaviour is typical of parabolas, whereas exponentials always grow (or decrease), and linear trends are, well, represented by a line.
Since the parabola has already reached its minimum, from there on it shall grow forever. So, in particular, we expect increased sales in 2014.
