I've got some line (Wulff Triangle Taper) that I've used only a few times (because I just haven't managed to get out fishing with this outfit as much as I would have liked), but is probably 7 years old. Does age alone cause deterioration in the line, or just the wear and tear of actually using it (and stepping on it, etc.)?

Or, put differently: what should I look for to tell whether I need to replace this line?

Thanks.

Barracuda