Note that the category "Tiers (Season 2)" shows the number of players in each tier based on their current rating at the end of Season 2. However, for the tiered rewards, it's the highest rating achieved that counts, so more players than shown will have reached the higher tiers.
Choose between solo and group, then use the dropdown menus to pick your server (or all servers together), and which chart you'd like to see. This link can be copied to return to your current selection. Participating players:Highest rating:
Average rating:
Median rating: