Why do I pay more for Creative Cloud?

Hello,

I subscribed to Creative Cloud for almost a year, and each month I pay € 30.74 (educational version). However, after checking on the Adobe website, the monthly award for Creative Cloud is € 15.99 (for the first year)!

How to justify such a difference? I've subscribed since January 2014, and in view of the price difference, Adobe would have taken me € 175.89 too much. This is not nothing, and I do not understand.

Can someone explain?

Kind regards,

Julien