Sunroof was optional on Passat regardless of model, in 96 and 97. In fact I'm almost sure that it was an option on all Passat B3 and B4 from 1990-1997.
However, cars without sunroof (preferred IMO) are very few compared with those that got the option. I would dare say that perhaps 10% of the B4 cars came without sunroof, and that might be optimistic. Most of the B3 cars were optioned up pretty well too, after all, it was the flagship at the time and the competition was pretty well optioned also.
Steve