If your using Access:
Add your new Fiscal_Year field to the first table and use it as the
base. Populate the new field with 2002. Then rename Site_2002
to something like Site_Data. Then select the Site_2003 table and
copy it and paste it to the Site_Data table name and select
Append data to existing table option. Then populate the
remaining empty Fiscal_Year fields with 2003.

If your using SQL server then:
Use the INSERT INTO statement.
Create the new filed Fiscal_Year in 2002. Populate it with 2002.
Then create a default on that field of "YEAR(GetDate())".
Then execute a statement like ...
INSERT INTO
Site_2003 (Col1, Col2, Col3...)
VALUES
(SELECT * FROM Site_2003)