It's small as a part of the economy. It's huge as a completely new thing. The US economy in total has been growing something like an average of 2.5% over recent years. Something that is all-the-growth-of-the-last-year-in-one-place is pretty significant.
AI didn’t happen in one year. Netflix’s famous recommender system challenge kicked off in _2006_! And “Big Data” was all the rage ten years ago. The category “AI” includes these things.