Which number replace - Math Riddle

Which number replaces the question mark?

30 6 2 3 2 12 2 ?

Explanation :

As you can see the lower number rows are always bigger than upper row ones with the difference going up by 3 with every step
34 - 32 = 2
32 - 27 = 5 (difference going up by 3 from last difference)
56 - 48 = 8 (difference going up by 3 from last difference)
? - 19 = 11 (difference going up by 3 from last difference)
So ? = 30