my $flipflop = 0;
print $q->table( {-border=>"1"},
    $q->TR([
        map {
            ++$flipflop % 2
                ? $q->td( {-rowspan=>"2"}, $_ ) . $q->td( $tab{$_}->[0] )
                : $q->td( $tab{$_}->[1] )
        } map { $_, $_ } sort keys %tab
    ])
);