[ravager]

Their data collection and compilation techniques are explained in detail here.

http://www.unodc.org/unodc/en/data-and-analysis/United-Nations-Surveys-on-Crime-Trends-and-the-Operations-of-Criminal-Justice-Systems.html

[TigersEye]

UN data collection systems? LMAO

They can only collate data given them by the nations in question. That data is collected in far different ways based on different parameters in every nation. You may think we're as stupid as you are but ...