[Antimatter]

Page 11 of this presentation from the Oxford Institute for Energy Studies has a nice graph showing crude quality over the last ten years, split into heavy sour, medium light/sour, light sweet and sour etc. Despite what we keep hearing about light sweet having peaked, the contributions appear more or less stable with the bulk of the increase in 2003 being delived by medium sour crudes. Medium sour is also the most common grade. This excludes NGLs, extra heavy, tar sands, refinery gain etc hence the lower total supply figure. However in the americas heavy sour has increased significantly over the last 10 years (pg 14). It would be interesting to see this data extending further back than 10 years.