It'll be 1996-1999 as you have the later style "Cannondale Stickers" and I bet you have the "C" decal on the head tube as well
Serial number for that will be stamped on the lower bottom bracket, so turn the bike over, select lower gears and don't move the wheel or chain guide so the cables go slack and undo the screw and slide the cable guide out the way.
They used the following numbering system from 1993-1999
E = 1993, F = 1994, G = 1995, H = 1996, I = 1997, J = 1998, K = 1999
A = January, B = Febuary, C = March, D = April, E = May, F = June, G = July, H= August, I = September, J = October, K = November, L = December