Write SQL query to solve given problem: In Harvard University, which year recorded the highest number of first-time, full-time, degree-seeking students in the cohort being tracked, minus any exclusions?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T2.year FROM institution_details AS T1 INNER JOIN institution_grads AS T2 ON T2.unitid = T1.unitid WHERE T1.chronname = 'Harvard University' GROUP BY T2.year ORDER BY SUM(T2.grad_cohort) DESC LIMIT 1