How common is it for somebody to get acute angle closure glaucoma?

Very uncommon. And preventable. One of the reasons we recommend routine yearly exams is to look for this problem, and prevent it. If narrow, occludable angles are found, a simple laser can eliminate the issue by creating an alternate pathway for fluid.
Not common. The usual underpinnings are hyperopic, over age 45, and more common in Asians. The condition is due to crowding of the anatomy of the front of the eye forward with iris dilation causing blockage of the normal interior fluid flow in the eye. It is a single digit occurrence in the susceptible. At your age, it would be extremely rare.
Uncommon. You are at greater risk for developing angle closure glaucoma if a blood relative has this condition or if you are far-sighted (hyperopic) this is not the same thing as needing reading glasses(presbyopic) if your distance glasses look like magnifying lenses, making your eyes appear bigger behind the lenses, then you are hyperopic. To diagnose a narrow angle condition gonioscopy is necessary.
Not very common. Angle closure glaucoma is about 10-15% of all glaucomas.
Not very. Acute angle closure is a very infrequent occurance. The incidence of this problem varies depending on the population studied. In the US, there are about 2 cases per 1000 people per year. Although the odds of angle closure are low, the outcome can be devastating to vision. Simple measures can be taken to further reduce the risk of this occurring. See your eye doctor to see if you are at risk.