Excel 2000

I've got a column of data.

I want the average of that data from the first line through any given line.
I'll give an example below.

How do I enter the cell range easily without having to enter the first cell
over and over again. I tried using "$", it didn't help when I cut and pasted.

example:

data average formula should look like:
2 2 =AVERAGE(A1:A1)
4 3 =AVERAGE(A1:A2)
6 4 =AVERAGE(A1:A3)
8 5 =AVERAGE(A1:A4)
10 6 =AVERAGE(A1:A5)

Thanks.