Yearly data are available not only for countries that report their trade data but also for the over 50 primarily low-income countries that do not report national trade statistics to COMTRADE. The trade of these countries has been reconstructed based on data reported by partner countries, and the statistics obtained are called mirror statistics.

While mirror statistics are the second-best solution, they are better than having no data at all. However, they have a number of shortcomings in comparison to nationally reported data:

They do not cover trade with non-reporting countries. As a result, mirror statistics hardly cover intra-Africa trade.
There is the problem of transshipments, which may hide the actual source of supply.

Mirror statistics invert the reporting standards by valuating exports in CIF terms (i.e., inclusive of transport and insurance) and imports in FOB terms (exclusive of these items).

In conclusion, the mirror statistics give an idea of the trade but do not reflect the exact reality. Consequently, one needs to be very careful in analyzing mirror data with direct data.