private function getConversionRateAggregation()
    {
        return $this->aggregationFactory->create(
            BucketInterface::TYPE_QUERY_GROUP,
            [
                'queries' => [
                    'sales' => $this->queryFactory->create(QueryInterface::TYPE_EXISTS, ['field' => 'product_sale']),
                ],
                'name' => 'conversion',
            ]
        );
    }