>>10597993870 years...
I'm a /his/ oldfag, but I know I'm not perfect, so anyone can help me.
Consider this:
TLOK stipulated that this amount of time has passed, and the atmosphere is close to the 20s mainly due to the Korra team's vehicle along with the Hong Kong Steampunk attempt.
If we think about it, the decáda of ATLA would be around 1850, but that is a bit strange since the Industrial Revolution began 30 years later in real life.
But then I remember that the environment is always closer to the East, so my opinion is half invalid.
Or TLOK is closer to the West ... or nothing is true and everything is permitted.