How many students apply each year at university of Arizona?

The University of Arizona doesn't release a single "number of applicants" figure each year. They report different application numbers depending on what they're counting (first-time freshmen, transfers, graduate programs, etc.). To find the number, you'd need to specify what kind of applicant you're interested in (e.g., undergraduate freshman applicants) and then consult the university's official admissions data, often found in their yearly reports or on their admissions website.