Calculation of per Capita on-the-fly - problems with SQL syntax

Hi there,

I need to calculate per Capita data on-the-fly. My table for a given
variable looks like this:

year | value | id_country
---------------------------------------
2001 | 123 | 1
2002 | 125 | 1
2003 | 128 | 1
2004 | 132 | 1
2005 | 135 | 1

2001 | 412 | 2
2002 | 429 | 2
2003 | 456 | 2
2004 | 465 | 2
2005 | 477 | 2

Now, I can't get the calc working correctly. I use the query below,
but a) it just takes too much time to come up with a result; and b)
the results has three lines for each country,
one with a value for y_2003 and a NULL for y_2002
one with a NULL for y_2003 and a value for y_2002
one with a NULL for both y_2003 and y_2002

SELECT DISTINCT
( CASE WHEN d.year=2003 AND pt.year=2003 AND pt.value <> '0' AND
pt.value IS NOT NULL THEN d.value / pt.value ELSE NULL END ) AS y_2003,
( CASE WHEN d.year=2002 AND pt.year=2002 AND pt.value <> '0' AND
pt.value IS NOT NULL THEN d.value / pt.value ELSE NULL END ) AS y_2002,
c.name
FROM
public_multiple_tables.agri_area AS d
LEFT JOIN
public_multiple_tables.pop_total AS pt ON pt.id_country = d.id_country
LEFT JOIN
countries_view AS c ON c.id = d.id_country
ORDER BY
name ASC

What am I doing wrong? Thanks for any advice,

Stef