title: Deleting top 5% and bottom 5% of all records
body: <p>I have a table that looks like this:</p>
  
  <pre><code>Customer ID, MDN, Plan, StartDate, EndDate, Term, SMS Usage, Voice Usage
  </code></pre>
  
  <p>Ordering by SMS Usage in ascending or descending order</p>
  
  <p>I want to delete the top 5% of all records, and the bottom 50% leaving behind the remaining 90% of customers</p>