Average Primary School Fees Was N10 (ten Naira)

So I bumped into some old school fees reciept as far back as 1985 and 1986. 1985 School Fees for second term was N7 (Seven Naira) while third term was N10 (Ten naira) Exam Fee was N5 (five naira) in 1986 On the average today, Primary School Fee is not less than N20,000. Correct me if am wrong.