in the meantime, please goolge google...
here is what I just found out http://www.nikonlinks.com/unklbil/n70.htm
"Film Rewind By pressing IN and Ps button; fast rewind or silent rewind is selectable; approx. 12 sec. per 36-exp. roll or 9 sec. per 24-exp. roll (fast rewind); approx. 22 sec. per 36-exp. roll or 18 sec. per 24-exp. roll (silent rewind)"
Shame on Nikon for such design!