Why does adding the CBP detail exceed the aggregate total?
You could be counting the same record two or three times since it appears at different summarization levels within the NAICS grouping. For example, an establishment in NAICS 316110 is also a part of NAICS 31611 and 3161, as well as in the manufacturing total. Therefore, summing the data at each NAICS level within this NAICS grouping would make the detail exceed the aggregate total.