my %aus = (2010 => 3100,
               2020 => 3200,
               2030 => 3300,
               2040 => 3400,
               2050 => 3500,
               2060 => 3600,
               2070 => 3700,
    );
    $portmap = exists $aus{$port}
        ? $aus{$port}
        : $port;