Every how often does the GMT bezel colors change?

[tough]

Just curious as to how often this happens.
I am considering a BLNR however want to make sure that a new combination doesn't come sometime soon this year.
I am not sure if there will be any combination that would beat the blue black as I love it over any other that were produced in the past, but I am still curious.

I assume when a new color combination is launched, the blue black production will be stopped, and it will then become a rare classic, slowly harder to find.
Another reason that I am leaning towards the BLNR over the LN.
Well this and the fact that the blue just has a unique factor which I love.
Don't think I would get bored of it, though I can't be sure.