Eh, it's a little tricky. A lot of research marketed under the "AI" umbrella would be categorized under cs.LG (https://arxiv.org/list/cs.LG/recent), cs.CV (https://arxiv.org/list/cs.CV/recent), cs.CL (https://arxiv.org/list/cs.CL/recent), and to a lesser degree cs.NE (https://arxiv.org/list/cs.NE/recent). Oh, and of course, cs.AI (https://arxiv.org/list/cs.AI/recent). Not every one of those areas has grown monotonically, but the growth in CV and CL especially has been explosive over the last ten years.