That would really depend on your subject and your University. You are most likely to find this information under your division's website. Alternatively, you could always get in touch with them if you are unsure where to access this.
For my degree, first year did not count towards my final grade, my second year contributed 40%, and my third year contributes 60%. However, I am aware of others whose first year account for a significant amount of their degree, so it is always best to check with your own University.
I hope this helps.
University of Kent Student Rep