public function findCompetencyCount(Scale $scale)
    {
        return $this->createQueryBuilder('s')
            ->select('COUNT(c) AS competencies')
            ->leftJoin('s.competencies', 'c')
            ->where('s = :scale')
            ->groupBy('s')
            ->getQuery()
            ->setParameter(':scale', $scale)
            ->getSingleScalarResult();
    }