Its an index of "Output". It does not specify what that output is. It is usually measured by domestic industrial capacity and utilization - how many widgets can your factory produce - the federal reserve does not survey output of domestically owned but internationally located factories.

Here is another graph that shows manufacturing output - this one specifies that it is measured by capacity and utilization. Its also a longer series to boot.

http://research.stlouisfed.org/fred2...=Medium&crb=on

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"Liberty is not a means to a higher political end. It is itself the highest political end - Liberty is the only object which benefits all alike, and provokes no sincere opposition - The danger is not that a particular class is unfit to govern. [I]Every class is unfit to govern[/I]. - Power tends to corrupt, and absolute power corrupts absolutely." - Lord Action