member ratings

I have noticed that some members are still rated as 'new members' when they have been members for a long time,(since 2010 for instance).
At what point do you progress from the new member tag?
Is it by the number of posts or the number of pics in your portfolio or just length of time as a member?
Not complaining as I've only been a member for 5 minutes, just curious.

It's to do with post count rather than time.
Not sure of the exact number but its a small amount of posts to progress to the next level.

Thanks Mike-P. BTW love the avatar.