public static function get_average_rating_for_product( &$product ) {
		global $wpdb;

		$count = $product->get_rating_count();

		if ( $count ) {
			$ratings = $wpdb->get_var(
				$wpdb->prepare(
					"
				SELECT SUM(meta_value) FROM $wpdb->commentmeta
				LEFT JOIN $wpdb->comments ON $wpdb->commentmeta.comment_id = $wpdb->comments.comment_ID
				WHERE meta_key = 'rating'
				AND comment_post_ID = %d
				AND comment_approved = '1'
				AND meta_value > 0
					",
					$product->get_id()
				)
			);
			$average = number_format( $ratings / $count, 2, '.', '' );
		} else {
			$average = 0;
		}

		return $average;
	}