Though this approach is far from being even remotely original, I have nevertheless decided to employ a marking system that is very close to the one that is used in European and American schools, colleges and universities because I feel that this is the one that most readers should be able to relate to quite easily. I therefore award each film that I review a score between 0% and 100%, and, based on the table below, a formal mark:

Score             Mark
85% ... 100%      Mark A: Excellent Pass
70% ... 84%       Mark B: Good Pass
55% ... 69%       Mark C: Clear Pass
40% ... 54%       Mark D: Bare Pass
25% ... 39%       Mark E: Clear Fail
0%  ... 24%       Mark F: Bad Fail

To have a bit more flexibility, I may add either a "+" (which means that the film is a tad better than the awarded formal mark)
or a "-" (which means that the film is a tad worse than the awarded formal mark).