Activity rank

Hello,Im here to ask about my Activity rank (Emissary) it's been a while and im still at that rank i have at the moment 5700+ achievement points so shouldn't i have a higher rank? im sorry but i just wanted to know how the ranking system works cause i really got no idea how much achievement points you need to have a certain rank.

You get additional 0.5 points for having account in good standing. When you get banned, you lose that bonus for 1 year.