  We have considered the statistical distributions of the volumes of the
different products exported by 148 countries. We have found that the form of
these distributions is not unique but heavily depends on the level of
development of the nation, as expressed by macroeconomic indicators like GDP,
GDP per capita, total export and a recently introduced measure for countries'
economic complexity called fitness. We have identified three major classes: a)
an incomplete log-normal shape, truncated on the left side, for the less
developed countries, b) a complete log-normal, with a wider range of volumes,
for nations characterized by intermediate economy, and c) a strongly asymmetric
shape for countries with a high degree of development. The ranking curves of
the exported volumes from each country seldom cross each other, showing a clear
hierarchy of export volumes. Finally, the log-normality hypothesis has been
checked for the distributions of all the 148 countries through different tests,
Kolmogorov-Smirnov and Cramer-Von Mises, confirming that it cannot be rejected
only for the countries of intermediate economy.
