Você precisa de uma consulta dinâmica para fazer isso:
SELECT SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 1 THEN 1 ELSE 0 END) AS Jan,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 2 THEN 1 ELSE 0 END) AS Feb,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 3 THEN 1 ELSE 0 END) AS Mar,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 4 THEN 1 ELSE 0 END) AS Apr,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 5 THEN 1 ELSE 0 END) AS May,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 6 THEN 1 ELSE 0 END) AS Jun,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 7 THEN 1 ELSE 0 END) AS Jul,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 8 THEN 1 ELSE 0 END) AS Aug,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 9 THEN 1 ELSE 0 END) AS Sep,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 10 THEN 1 ELSE 0 END) AS Oct,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 11 THEN 1 ELSE 0 END) AS Nov,
SUM(CASE WHEN EXTRACT(MONTH FROM dateshipped)::int = 12 THEN 1 ELSE 0 END) AS Dec
FROM Shipments
WHERE EXTRACT(YEAR FROM dateshipped)::int=2016
