The number of raw traceroute log files that contain any information and those kept.
The number of source nodes, destinations and operators involved in the measurements.
The number of complete traceroutes:
By the definition the NAT gateway must belong to an AS, which relates to the given operator. In few cases it may happen the NAT gateway candidate has an AS resolved that does not conform with this expectation. We need to filter them out and we do it manually as there is no strict rules to the string representation of the various AS-s.