In Yale University, what is the average number of Black students per year who were bachelor's/equivalent-seeking cohort at 4-year institutions between 2002 to 2005?
Yale University refers to chronname = 'Yale University'; average = DIVIDE(COUNT(race = 'B' WHERE cohort = '4y bach AND year BETWEEN 2002 AND 2005), 3); Black refers to race = 'B'; bachelor's/equivalent-seeking cohort at 4-year institutions refers to cohort = '4y bach'; between 2002 to 2005 refers to year BETWEEN '2002' AND '2005';
SELECT AVG(T2.grad_cohort) FROM institution_details AS T1 INNER JOIN institution_grads AS T2 ON T2.unitid = T1.unitid WHERE T1.chronname = 'Yale University' AND T2.year BETWEEN 2002 AND 2005 AND T2.race = 'B' AND T2.cohort = '4y bach'