350.23.5. A person’s percentage total value added in respect of customers’ goods for a fiscal year of the person is the amount expressed as a percentage that would be determined for the fiscal year by the formula in section 350.23.4 if the total determined under subparagraph 1 of the second paragraph of that section did not exclude any amounts that are reasonably attributable to the performance of basic services or the provision of added property used in the performance of basic services.