title: Calculate difference and percent change on a list of controls
body: <p>What would be the best way, within VBA, to accomplish the following:</p>
  
  <ol>
  <li>I have two groups of controls which represent a historical and a current data set</li>
  <li>I am using the control.tag field to dictate which is historical and which is current, as an example:
  
  <ul>
  <li>Group 1 contains (Historical Data)
  
  <ul>
  <li>Historical - Number of People</li>
  <li>Historical - Number of Cars</li>
  <li>Historical - Number of Houses</li>
  </ul></li>
  <li>Group 2 contains (Current Data)
  
  <ul>
  <li>Current - Number of People</li>
  <li>Current - Number of Cars</li>
  <li>Current - Number of Houses</li>
  </ul></li>
  </ul></li>
  <li>I would like to loop through both sets of controls and provide the following for each set
  
  <ul>
  <li>Change in value (ex: (Current - NUmber of People) - (Historical - Number of People))</li>
  <li>Percentage change (ex: (((Current - NUmber of People) - (Historical - Number of People)) / (Historical - Number of People)) * 100)</li>
  </ul></li>
  <li>I'm hoping to avoid having to call each control manually but would rather want to loop through all controls, find the ones that match in each set and do the math.</li>
  </ol>
  
  <p>Thanks in advance!</p>