Gradebook Classic does not display item's class average when grades are set to display as percentage

Steps:

• Open Gradebook Classic tool
• click gradebook setup
• under "How will graders enter grades into this gradebook?" select Percentages
• save
• go back to gradebook items
• create a gradebook item (if one doesn't exist)
  • add some grades to it
• The gradebook item's "Class Average" is not displayed
• click the gradebook item to view it's details
• The gradebook detail page's "Class Average" is not displayed