How many years has the University of Tennessee been in division 1A?

The University of Tennessee has been in the top tier of college football, currently known as the Football Bowl Subdivision (FBS), since its inception. While the naming conventions have changed over time (Division I-A, Division I FBS), the Vols have *always* been at the highest level of competition. Therefore, there's no specific year to mark their entry into Division I-A/FBS as it's been their consistent classification throughout their football history.