Just by Thinking of Klose the graph I can tell you is incorrect. It worries me that such a well known player would go unaccounted for. leading me to believe not much effort went in to developing it.

It fails to mention or discount players born outside with parents of the country and vice versa: players who were born in the country and their parents are from foreign countries. Some examples: Gonzalo Higuaín Mariano Andújar, David Trezeguet.

It also fails to mention countries that most players do not play in, that would have been good to know...

It seems to fail to mention players whom are foreign and played the World Cup (Cacau for example)

Finally the graph fails to account for players whom played less than 5 matches making their contributions next to nothing in their totality.