how to average multiple averages that can contain zeros

HI I have attached image illustrating what I am trying to achieve. I have a list of data in column E, if I take the average of [E4:E9] I get 11.67. However I require the averages to first be calculated in pairs as displayed in column G, I then need the averagers in column G to be averaged giving a final average of 13.75.

It all works fine until I get both points in a pair with missing data thus returning "#DIV/0!"

I have huge amounts of data I require this to be done for, so I was hoping there there would be a function that I could insert at the bottom of column E that would give the average of 13.75 so i can then drag it across all the data.

Thanks in advance