well what it does is that it takes the total numbers of people who voted already, in this case that's 25 atm, and then it calculates the % of users who have voted for the show. For instance, a show with one vote will have 4%. The reason why the sum goes over 100 is because there are multiple votes allowed
And so it only calculated the percentage of users who voted on that show. In the example of the show that got 1 vote, the percentage of users who voted for the show will be 4%.
So the question to your answer is: Yes it would be weird if people were only allowed to vote for 1 show, but it isn't weird because people are allowed to vote for one than 1 show, and every vote gets as much weight as any other vote. For instance is someone votes for show X and 9 other shows also. The vote for show X will be worth as much as the vote of another user, who only voted for show X. It's the number of users who vote for the show that count.