You can ensure you are not in that 15% by undertaking independent aptitude tests through GAPAN.
Be careful there! The GAPAN test just helps ensure that your brain is wired up right to fly aeroplanes, particuarly in instrument conditions. The GAPAN test does not provide any indication that you will be profiled appropriately through psychometric testing or that you are team orientated or any of the myriad of tacit and soft skills that employers probably look for.