9999=4 8888=8 1816=3 1212=0 1919=?

Here comes a killer puzzle :

9999=4
8888=8
1816=3
1212=0
1919=?

Let's see can u crack this one...

HINT: You don't have to be a Mathematical Genius to solve this... Just Observe... Observe...
👍👍
Pls ans with reason

Click here for Answer

2 = The number of circles in the number given