generally, there's 5 to 35 miligrams per 8 oz. cup of jasmine tea, depending on if it's made from green tea or oolong, as the aforementioned leaves are exposed to jasmine flowers' fragrance.
if you want to reduce the amount of caffeine in your tea, use loose leaf and steep for a minute, then pour out and steep again to your liking. it'll probably take a little longer to get it right after it's been steeped once.
80% of the caffeine is washed away in the first steeping.
also, the caffeine in tea is metabolized more slowly than coffee, so you should not get the same jitters and increased heart rate.
in nomine patri, et fili, et spiritus sancti.
Meh nom eh noh...doot dooooo do do do.