Yes, it is changing every year it depends on the number of students get the score than it goes up and not then it goes down it totally on the number of students. For example, if 10000 students score more than 61.8 then that time your rank is 10001 and if 1000 student only scores above 61.8 then that case your rank is 1001 this huge gape I hope you understand. So no need to worry about it happen every.

Good Luck.