title: Getting Weighted Average within a category with multiple sub categories
body: <p>Joe owns a worldwide DVD rental store. He has stores throughout the globe in different regions. Each month he likes to see if his equipment in his stores is up-to-date by finding the percentage of his inventory with a certain status of &quot;Current,&quot; &quot;Needs Update,&quot; and &quot;Must Go&quot; for each region. This helps ensure his customers have the best experience in his stores.</p>
  <p>Bill, his assistant, wants to build a SQL query that will show Joe the percentage of equipment in each region and their status. The guy before him used an excel to do this but Bill thinks SQL and then an SSRS report that would allow Joe to select which region he wants to view would impress him. He wants to have it dynamically transition from months to quarters as the year progresses in the report. This is what Bill has been able to come up with so far:</p>
  <p>Comparing it to the excel from before, everything is correct and his SSRS is working perfectly all except for North America, which has percentages that are slightly off. He is thinking that a weighted average for the subregions in North America would fix this to get the percentage correct because some subregions are bigger than others.</p>
  <p>How would Bill go about calculating the weighted averages each of the regions in North America?</p>