This was last revised 2004-1-2, based on information mostly 2003-11-8 (and some earlier); be aware it's out of date even before I am doing this editing, and probably in some respects now actually incorrect!
Figures thus were noted2003-11-8 inLondon - and were the lowest I found - allow at least ~ 10-15% margin;
thus 2003-8-16
thus 2003-3-8
otherwise(mostly) earlier (various places) and've probably dropped more.