Need Help With Adding A Duplicate Record Count Column To Query

I am attempting to create a simple recordset that would return the
number of duplicates that exist in a table with a single column. For
example if I had a table like the following:

ID Reference Amount
1 123456 1.00
2 123456 2.00
3 123 1.00

I would like to get the following result:

ID Reference Amount RecCount
1 123456 1.00 2
2 123456 2.00 2
3 123 1.00 1

Please help!
Thanks,
Shawn