Inspirado em outras respostas, mas talvez melhor organizado:
SELECT *,
brcht + cana + font + nr AS total
FROM (SELECT insee,
annee,
SUM(Coalesce(brcht.nb, 0)) brcht,
SUM(Coalesce(cana.nb, 0)) cana,
SUM(Coalesce(font.nb, 0)) font,
SUM(Coalesce(nr.nb, 0)) nr
FROM brcht
full outer join cana USING (insee, annee)
full outer join font USING (insee, annee)
full outer join nr USING (insee, annee)
GROUP BY insee,
annee) t
ORDER BY insee,
annee;
Dando:
insee | annee | brcht | cana | font | nr | total
--------+-------+-------+------+------+----+-------
036223 | 2013 | 0 | 0 | 0 | 1 | 1
036223 | 2014 | 0 | 0 | 0 | 1 | 1
036223 | 2017 | 0 | 1 | 0 | 0 | 1
086001 | 2013 | 0 | 0 | 0 | 1 | 1
086001 | 2014 | 0 | 0 | 0 | 2 | 2
086001 | 2015 | 0 | 0 | 0 | 4 | 4
086001 | 2016 | 0 | 2 | 0 | 2 | 4
(7 rows)
