Hmmm, my studies have shown rumours of between 20000 kays and 18000 miles... From memory, the nismo page states 20, so that'd be the best bet.
Also, to anyone who said that i must have been mistaken, I most certainly was not. Turns out, the car was brought by a private buyer and has been sold before delivery to him to an unknown buyer for considerably less than the suggested prices. 6000 kays, absolutely immaculate. Also, there were only 20 made.