What is the percentage of the international students in University of Oslo in 2015?
percentage of the international students refers to pct_international_students; in 2015 refers to year = 2015; in University of Oslo refers to university_name = 'University of Oslo';
SELECT T2.pct_international_students FROM university AS T1 INNER JOIN university_year AS T2 ON T1.id = T2.university_id WHERE T1.university_name = 'University of Oslo' AND T2.year = 2015