Personal Use of Auto

In determining business use % of a personal vehicle used in a business that was only open part of the year, is the denominator the total miles driven for the year by that vehicle regardless of if business or personal, or is the denomintator specific to the total miles driven while the business was open?  Example I owned my car all year and drove 5,000 miles over the 12 months for all purposes.  My business was opened in Nov and I drove 1,500 business miles, and 2,000 of the 5,000 all-pupose miles during the time the business was open.  In determining business use %, do divide 1,500 by 5,000 or 2,000?  Assume I'll be using actual expense method and taking a depreciation deduciton.  Thank you!