title: Calculate growth percentage between previous year and current year
body: <p>I want to calculate the growth percentage over the previous year. </p>
  
  <p>Table structure:</p>
  
  <pre><code>CustomerName | Sum_1415 | Sum_1516 
  </code></pre>
  
  <p>I have tried this query:</p>
  
  <pre><code>select CustomerName, SUM(Sum_1415), SUM(Sum_1516), 
      round(sum(Sum_1516)-Sum(Sum_1415)/(select sum(Sum_1415) from dummy),2) as Percentage 
  from dummy 
  group by CustomerName 
  order by Sum_1415 desc 
  limit 15
  </code></pre>