Excel Data Grouping and Evaluation

I have a set of data that looks like this:

ID Value
12345_12_345 7
12345_12_345 10
12346_12_345 9
12346_12_345 10
12346_12_345 3
12347_12_345 3
12347_12_345 5
12347_13_345 10
12347_13_345 3
12347_13_346 8
12347_13_346 8

I need to create a macro that will march through the ID column and identify groups of similar data. Once a group is identified, i need to take the average of the value of that group, print it to a column adjacent to the values, and move to the next group.

Any thoughts?

Not sure what

print it to a column adjacent to the values

this means, but I would investigate pivot tables if I were you.

I've looked into that but i have 60,000 data points in my set. I think given this large value a macro would be able to do the task more efficiently.

"Print to a column adjacent to the set"

By that I just mean post the value of the group average in the next column.

Irrespective of what you might think, you'll find that pivot tables are probably a very efficient way of doing this.

If you want someone to provide a macro, I suggest you attach a sample workbook.