Sources: where I found this info:
Most of the figures in my quiz came from the United Nations Environment Programme Global Environment Outlook 2000 report (GEO-2000). You can see this for yourself at UNEP's site.
Some population info (1994) came from the World Guide CD-ROM 1997, Hillco Media Group, Uppsala, Sweden.
The statistics on traffic accidents came from International Road Traffic and Accident Data (IRTAD) site