In 2018, 3 is the most common age for an American (U.S.) Arianna who is registered female with the Social Security Administration. It is the 791st most common female first name for living U.S. citizens.
We have an Arianna who is 15 years old. We pronounce it ARE-ee-ah-nah, not AIR-ee-ah-nah... Most everyone says it 'Air'. Sometimes I think if I would have spelled it with one N, this may not have happened as much. Anyway, she mostly goes by Ari. Full name is Arianna Elizabeth. She has always liked her name a lot. It's not super common in our area or schools. This is her first year of high school, and there is one other Arianna (senior) in the school. Previously, she has been the only one.
In Italy Arianna was hardly ever used till the 1970s. Today it is common, without being overused (21th most popular name in Italy in 2004, 20th in 2006).