Return the metrics assertion coverage

def metrics_asserted_pct(self):
        """
        Return the metrics assertion coverage
        """
        num_metrics = len(self._metrics)
        num_asserted = len(self._asserted)

        if num_metrics == 0:
            if num_asserted == 0:
                return 100
            else:
                return 0

        return num_asserted / num_metrics * 100