public function registerDefaultStats($filename)
    {
        // TODO Just register the filename and load the content after?

        if (!file_exists($filename)) {
            throw new Exception(sprintf('File for defaults stats with filename "%s" is not found', $filename));
        }

        try {
            $yaml = Yaml::parse(file_get_contents($filename));
        } catch (ParseException $e) {
            throw new Exception(sprintf('Unable to parse the YAML string: %s', $e->getMessage()));
        }

        if (!isset($yaml['default_stats']) && !is_array($yaml['default_stats'])) {
            throw new Exception(sprintf('The defaults stats file "%s" must have "%s" key as root',
                $filename,
                'default_stats'
            ));
        }

        $this->defaults = new Collection(
            array_merge($this->defaults->toArray(), $yaml['default_stats'])
        );
    }