Among the universities in Australia, how many of them have a student staff ratio of over 15 in 2011?
in 2011 refers to year 2011; in Australia refers to country_name = 'Australia'; student staff ratio of over 15 refers to student_staff_ratio > 15
SELECT COUNT(*) FROM university AS T1 INNER JOIN university_year AS T2 ON T1.id = T2.university_id INNER JOIN country AS T3 ON T3.id = T1.country_id WHERE T3.country_name = 'Australia' AND T2.student_staff_ratio > 15 AND T2.year = 2011