title: calculate difference and percentage
body: <p>I have following data , numbers recruited/applied for a particular office, and would like to find the difference between previous and current year and their percentage increase or decrease.</p>
  
  <p>Mentioned the formulas to use in brackets in expected output.</p>
  
  <pre><code>Office      year        recruited       applied
  Pune        2015            10            15
  Pune        2016            7             20
  Mumbai      2015            10            23
  Mumbai      2016            15            18
  </code></pre>
  
  <p>My expected output should be like:</p>
  
  <pre><code>Office      Difference      %recruited
  Pune        -3  (7-10)      -30%(7-10/10)
  Mumbai      5(15-10)         50%
  </code></pre>
  
  <p>Please help.</p>