title: Rails calculate percent true from a set of boolean values
body: <p>I am fairly new to using Ruby with the Rails framework and I have a question:</p>
  
  <p>Using rails with postgresql, I have a customer model that has a boolean attribute named eft.  I am wondering how I would go about calculating the percent of customers that have an eft value of true.</p>
  
  <p>Thanks for the help!</p>