Geostrategic power index - variable 4: Economy (GDP)

The fourth variable visualized and included in the calculation  of the geostrategic power index is the economy (GDP). The rationale for including the economy and its size in the calculation of any power index is i think obvious as it both indicates potential for spend on domestic armed forces and equipment as well as ability and potential for funding and supporting allies and friendly countries. On top of this comes the civilian impact and influence from trade, FDI flows etc (arguably power components) for which GDP size can act as a crude but sufficiently accurate indicator for the purpose of calculating a power index. 
The GDP map visualizes the size of the economy in billion USD and as a share (%) of world total GDP for each country. Click on corresponding bubbles for details. USA, China and Japan in that order have the largest economies currently.
The map also shows that the world centroid or center of gravity for economy (GDP) is located in the South East of the european part of Russia (Kazan).