how to get overall total of several tables?

[ales]

SELECT sum(totpas) overall
FROM
(
select ' CAA 97' tname, sum(nw1w2) totpas from caa97
where apt='MAN'
union all
select ' CAA 98', sum(nw1w2) from caa98
where apt='MAN'
union all
select ' CAA 99', sum(nw1w2) from caa99
where apt='MAN'
union all
select ' CAA 00', sum(nw1w2) from caa00
where apt='MAN'
union all
select ' CAA 01', sum(nw1w2) from caa01
where apt='MAN'
)