A graph showing the price of West Texas Intermediate (WTI) crude oil over time, with a downward trend. The graph has a scale on the left side showing the price in dollars per barrel, and the years are marked on the bottom. The graph starts in 2006 and ends in 2013. The price of WTI crude oil is shown to have been around $60 per barrel in 2006, and it has been steadily decreasing since then, reaching a low of around $30 per barrel in 2013.