In the table given below Marks of 4 students in 5 different Subjects are given. Total Marks of each subject is 100.

	Math	English	Hindi	Social science	Science
S1	98	60	85	75	92
S2	97	65	80	80	90
S3	95	70	85	70	95
S4	96	62	70	80	90

What is the difference in average marks of students S1 and S4?