total excess distribution

(i) the amount of the distributions in respect of the stock received by the taxpayer during the taxable year, over

(ii) 125 percent of the average amount received in respect of such stock by the taxpayer during the 3 preceding taxable years (or, if shorter, the portion of the taxpayer's holding period before the taxable year).

For purposes of clause (ii), any excess distribution received during such 3-year period shall be taken into account only to the extent it was included in gross income under subsection (a)(1)(B).