title: Need to calculate percentage of total count in SQL Query
body: <p>I have a a table where I have two columns, one is a Date Time column (Test_Complete) and another is alphanumeric Record ID column (RecordID).</p>
  
  <p>I need to prepare a count of recordIDs which were processed on a monthly basis. I have already created a query for that.</p>
  
  <pre><code>SELECT (Format([Test_Complete],"mmm"" '""yy")) AS Evaluation_Month, 
  Count(tbl_TestStatus.Record_ID) AS CountOfRecord_ID
  FROM tbl_TestStatus
  WHERE (((tbl_TestStatus.[Test_Complete]) Is Not Null))
  GROUP BY (Format([Test_Complete],"mmm"" '""yy")),
  (Year([Test_Complete])*12+Month([Test_Complete])-1);
  </code></pre>
  
  <p>This query works well and gives me output like this:</p>
  
  <pre><code>Evaluation_Month     CountOfRecord_ID
  ------------------   -----------------
   Jan'12                   20
   Feb'12                   90
   Mar'12                   40
   Apr'12                   50
  </code></pre>
  
  <p>Now what I need is to calculate the percentage of CountOfRecord_ID value against each Evaluation_Month and append the percentage with the value in Evaluation_Month data. </p>
  
  <p>In the above resultset, the sum of all the CountOfRecord_ID is 200. so the percentage needs to be calculated considering 200 as 100%, such that my result looks like this:</p>
  
  <pre><code>Evaluation_Month     CountOfRecord_ID
  ------------------   -----------------
   Jan'12 (10%)                20
   Feb'12 (45%)                90
   Mar'12 (20%)                40
   Apr'12 (25%)                50
  </code></pre>
  
  <p>How can I modify my SQL query to achieve this?</p>