Home Office Expenses - what do I enter?

The entry for home office expenses is confusing.  It was for me last year as well.  I get entering the square footage for the office vs entire house.  The next screen asks for expenses for the entire house.  Again, that is straight forward.  The 3rd screen asks for expenses only related to the home office.  Does TurboTax calculate the expenses (taxes, mortgage interest, utilities, repairs, etc.) automatically or am I supposed to enter the percentage of total expenses based on the first screen (square footage calculation).

For example:  My wife uses 20% of the home (the basement) to run her business.  Taxes are $10,000.  Do I enter $2,000 on the last screen described above or do I leave it blank for TurboTax to calculate that figure for me?