Subjects lectured per week

I am currently lecturing at a private college where I am obliged to lecture, on average, 12 distinct subjects per year at both diploma and degree level. I lecture 6 to 8 subjects per week or around 4 or 5 unique subjects per day across all graduate levels (first, second and third year students). Some of these classes are repeated identically up to 7 times each week for 7 different groups of students for around 30 to 35 lecturing hours per week.

I am currently feeling a little overwhelmed by the workload. Is this normal for a private education institution?