Sum the excess value in a row of cell

Hello,
i need to add sum of values as shown in the below example

Ex:

Given Values

8
8.5
9
9.5
8.5
9

From the above set of numbers i need to sum the value which is greater than 8. the answer should be 4.5
(0+0.5+1+1.5+0.5+1 = 4.5)

Please help me what simple function can be used in excel'07 to make the above calculation

Regards