US Share of GDP Constant Over Last 40 Years---MUST Be A Bad Thing...RIGHT???

 No, not necessarily...I analyzed the graph wrong (yes, I can make a mistake)...I looked at it as GDP growth as opposed to SHARE of World GDP...A fellow AP Economics teacher Jason Welker, set me straight.  His explanation below clarifies what this graph REALLY says....

"I'm not sure we should be so troubled by the flat trend lines for Latin America and Africa. Keep in mind, this is not GDP, this is share of world's GDP. Unlike total output, which is NOT a zero sum concept, share of total output IS a zero-sum concept. A gain made by one part of the world is only possible by a loss made in another part of the world. The decline of the EU 15's share of world GDP does not mean that the EU 15 experienced a decline in output. In fact, the EU 15 have grown steadily over the last 40 years. Their downward sloping curve indicates that they have grown more slowly than the rest of the world, that's all. So the flat lines for Africa and Latin America in fact indicate that those two regions have grown more rapidly than Europe. Although it doesn't look like it on this graph, the "poor south" is actually catching up with the "rich north" as average growth in Europe lags behind that in the south.
It's a bit misleading to interpret the graph in this way, but the gains in Asia have in a way come at the expense of gains in Europe, but only in that they now have a larger share of a MUCH larger pie! All regions have grown, and Latin America and Africa have grown AS quickly as the US, and MORE quickly than Europe. Good news!"