title: I need to get the sum of next 5 rows that are order by one specific column
body: <p>actual table</p>
  
  <pre><code>YEAR  TOT
  ----  ---
  2001    1
  2002    2
  2003    3
  2010   10
  2011   11
  2012   12
  2013   13
  2014   14
  2015   15
  </code></pre>
  
  <p>Now Expected Results :</p>
  
  <pre><code>YEAR  TOT  Exp_res
  ----  ---  -------------------
  2001    1  1+2+3+4+5      = 15
  2002    2  2+3+4+5+6      = 20
  2003    3  3+4+5+6+7      = 25
  2010   10  10+11+12+13+14
  2011   11  11+12+13+14+15 
  2012   12  12+13+14+15 
  2013   13  13+14+15 
  2014   14  14+15 
  2015   15  15
  </code></pre>