Why not do a self join and do it all in the select?
Select a.year, a.month1, a.month1/b.month1, a.month1/c.month1 ...
From table1 a, table1 b, table1 c
where b.year = a.year-1
and c.year = a.year -2
and a.year = 2001
Or am I missing something?
FYI... you would probably want your select...