We updated it after season 1 (or 2? ...a while ago). I don't have a pretty graph handy, but the breakdown by percentage of players is...
Bronze: 7%
Silver: 35%
Gold: 35%
Platinum: 15%
Diamond: 7%
Master: 1%
Edit: I should note, those are the targets. Actual numbers vary a bit as the season goes on (for example, hardcore players tend to place earlier than more casual players), but roughly fall in line with that over time.
https://www.reddit.com/r/heroesofthestorm/comments/82p1h5/ranked_player_distribution/
We updated it after season 1 (or 2? ...a while ago). I don't have a pretty graph handy, but the breakdown by percentage of players is...
Bronze: 7% Silver: 35% Gold: 35% Platinum: 15% Diamond: 7% Master: 1% Edit: I should note, those are the targets. Actual numbers vary a bit as the season goes on (for example, hardcore players tend to place earlier than more casual players), but roughly fall in line with that over time.