The sales factor is a fraction, the numerator of which is the total sales of the taxpayer in this state during the tax period, and the denominator of which is the total sales of the taxpayer everywhere during the tax period other than sales of either:
1. A foreign corporation which is not itself subject to the tax imposed by this title, unless the corporation is subject to the tax as a member of an Arizona affiliated group, as defined in section 43-947.
2. An insurance company that is exempt from tax under section 43-1201.