This chart - hash rate means total hash rate of All minor?
I think the most significant factor for difficulty and block generation time is the hash rate of the biggest mining pool not total hash rate of all of minors.
I want to assure it that if there is a mining pool have 30% of total hash rate and this mining pool is the biggest pool.
Then this mining pool will succeed to find target hash value faster than others(stochastically).
Therefore, I think difficulty for block generation time will be set by this mining pool.
As a result, if other mining pools don't have a enough hash rate for example, 10% of total hash rate, then stochastically, it will takes 3 time more to find a traget value.
So i think the most significient factor is hash rate of the biggest mining pool
Am i thinking well?
And it seems like out of title, but i have one more question.
If fork is happened, Mining pool can recognize fork is happened?