How many times more was the number of students of University of Ottawa than Joseph Fourier University in 2013?
Joseph Fourier University refers to university_name = 'Joseph Fourier University'; University of Ottawa refers to university_name = 'University of Ottawa'; in 2013 refers to year = 2013; how many times more refers to DIVIDE(SUM(num_students where university_name = 'University of Ottawa'), SUM(num_students where university_name = 'Joseph Fourier University'))
SELECT CAST(SUM(CASE WHEN T2.university_name = 'University of Ottawa' THEN T1.num_students ELSE 0 END) AS REAL) / SUM(CASE WHEN T2.university_name = 'Joseph Fourier University' THEN T1.num_students ELSE 0 END) FROM university_year AS T1 INNER JOIN university AS T2 ON T1.university_id = T2.id WHERE T1.year = 2013