Yes it shows 1 because the sum(RingingTime) and Sum(Total RingingTime) has the same value.
Let me explain. Cosider you have data as below.
User ID RingingTime.
So now when you say sum(RingingTime) will be 60 and sum(Total RingingTime) = 60
So you are getting 1.
But for average your expression should be sum(RingingTime)/Count(RingingTime or UserID)
This will give you 60/3 i.e 30. which is the avg.
So please make changes in your expression by considering above calculation of avg.
Hope this helps.