One problem that jumps out at me is the ; that you added to the end of your SQL statement. For clarity's sake, let's break this down a bit by separating the SQL from the $sth, and fixing that extra semi-colon. If I were you, I would also unquote the numbers if they are going into a numeric field, and also use place-holders.
my $sql = "
INSERT into Standard_population (
Standardisation_type,
Male_00_04,
Female_00_04,
Male_05_09,
Female_05_09,
Male_10_14,
Female_10_14,
Male_15_19,
Female_15_19,
Male_20_24,
Female_20_24,
Male_25_29,
Female_25_29,
Male_30_34,
Female_30_34,
Male_35_39,
Female_35_39,
Male_40_44,
Female_40_44,
Male_45_49,
Female_45_49,
Male_50_54,
Female_50_54,
Male_55_59,
Female_55_59,
Male_60_64,
Female_60_64,
Male_65_69,
Female_65_69,
Male_70_74,
Female_70_74,
Male_75_79,
Female_75_79,
Male_80_84,
Female_80_84,
Male_85_plus,
Female_85_plus)
VALUES(
'EuropeanStandard',
'8000',
'8000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'7000',
'6000',
'6000',
'5000',
'5000',
'4000',
'4000',
'3000',
'3000',
'2000',
'2000',
'1000',
'1000',
'1000',
'1000')";
my $sth = $dbh->prepare($sql) or die $dbh->errstr;
$sth->execute() or die $dbh->errstr;
$dbh->commit();