Percentage for each star/vote (statistics)

Hi,

I try to create cleanly statistics of the votes with fivestar and voting api, for example:

5 stars : 25 votes (25%)
4 stars : 50 votes (50%)
3 stars : 10 votes (10%)
2 stars : 10 votes (10%)
1 star : 15 votes (15%)

There is a function for that (votingapi_results_alter) ?
What is the way to be followed?

Thanks in advance