Calculating the rating for clans!

Good day to you all, ladies and gentlemen. After the preliminary calculation of clan ratings, I decided that we need to introduce a time limit for accumulating clan ratings, i.e., specify the rating for a certain period, such as a year. Why is this necessary? Let me explain: Let's say we have a clan called "Winners," and this clan has been leading for a long time and has significantly outpaced other clans in terms of cumulative and average rating. Then, at some point, this clan "dies," meaning its members stop participating in tournaments on our portal. However, due to their huge accumulated rating, they can remain in the top positions of the "hit parade" for a long time. To avoid this, I propose introducing a time limit, i.e., the cumulative rating starts being calculated from January 1st and ends on December 31st. And at the end of the year, we can summarize the results, like: "Best Clan of 20xx," "Best Player of 20xx," "Most Active Clan of 20xx," etc. I look forward to your comments. Sincerely.