Economic index plot

http://www.themacrotrader.com/category/asset-allocation/
This is an index value plot.  The dark blue line is the Global Macro Index and the purple line is the SP500.  Both variables show their performance in time if you had an initial investment of $1000 in each starting in October 2007, which is the beginning of the economic recession.  This is an index because it starts at an arbitrary benchmark and the information that it is telling you is the relation to that benchmark through time.  The Global Macro Index never goes below the starting value, while the SP500 has always stayed below the starting value.