Calculating Nisaab for Zakat by an international standard

Is the Nisaab of Zakaat different for different countries? Should it be the same for a person of Somalia where most of the country is below the UN established poverty line and for Switzerland, where hardly anyone is below the poverty line? The Nisaab set by Mohammad for the camel, the goats and the gold, all were equivalent at the time?  Has someone done a real time-value calculation of the money worth at that time for the Nisaab set and it's translation to these times? As you might have noted, I am trying to figure out how should it be implemented on an international level? 

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

 

The minimum amount liable for Zakat does not differ from one country to another. Islam has set a fixed amount for Zakat which excluded any need to make Ijtihaad (a juristic opinion on matters which are not specified in the Quran or the Sunnah) to calculate it. For instance Zakat for gold is 85 grams and whoever possesses less than this amount is not obliged to pay Zakat. The same thing applies to cattle and other wealth, there is a definite minimum amount liable for Zakat and it is not permissible for anyone, regardless of his position, to alter it, to increase it or decrease it for any reason. Zakat is exactly like the fixed prayers, they are five daily prayers and they are not subject to an increase or a decrease; its units (Raka'h) are known and specified, for instance Fajr is 2 Raka's, and it is not acceptable to pray one Raka'h due to tiredness; the same thing applies to other prayers [and other unchangeable religious obligations].  

Allaah knows best.