How to get average of column values in laravel

Lets say I have this column

star
----
1    
3    
3    
1    
2    
5    
3

It has seven rows and there are integer values! I want to have it added and divided by the rows there are.

How do I do it in laravel. I can do it in plain php but I want to learn it in laravel.

via Chebli Mohamed