[How Can I get back 5 stars rating?]

Hi, I have 57 (5 stars) 5 (4.7 stars) 2 (4.3 stars) and 1 (4 star) ratings on my gig. 

There are total 65 reviews on my gig with a 4.9 rating. How many 5 star reviews do I need to get back 5 star rating on my gig?

Kindly guide If someone know properly about it.

Thanks