How is "Effective Tax Rate" calculated in the TT "Federal Tax Return Summary" section?

When you print or save your tax returns, TT has a "Federal Tax Return Summary" section on an introductory page with these figures on it:

 

Adjusted Gross Income
Taxable Income
Total Tax
Total Payments/Credits
Payment Due
and...

Effective Tax Rate

 

How is "Effective Tax Rate" calculated?

 

I tried dividing the "Total Tax" by both the "Adjusted Gross Income" and by the "Taxable Income," and neither result matched the "Effective Tax Rate" shown in that section.  Both percentages were higher than the "Effective Tax Rate" shown.