Calculate slopes between two points
<p>How can I calculate the slope between two data points?</p>

<p>My values look like this:</p>

<pre><code>2010 |  2011 |  2012 |  2013
23.5 |  4    |  0    |  1.5
</code></pre>

<p>and so on. So, to each year belongs a value - AUC.</p>