def read_tpld_stats(self):
        """
        :return: dictionary {tpld index {group name {stat name: value}}}.
            Sea XenaTpld.stats_captions.
        """
        payloads_stats = OrderedDict()
        for tpld in self.tplds.values():
            payloads_stats[tpld] = tpld.read_stats()
        return payloads_stats
:return: dictionary {tpld index {group name {stat name: value}}}.
            Sea XenaTpld.stats_captions.