Currency Index Indicator

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//  Copyright by HPotter v1.0 04/07/2014
// The currency index represents the change in one currency by reference to all other 
// foreign currencies. The index is calculated by taking the average of the variations 
// in one currency by reference to the others. Represented in graphical form, it allows 
// for easy visualization of the individual trends in each currency. 
// The index of the currencies is a simple arithmetic average of the variation in each pair. 
// For each index, to have fixed the value 100 on 1 January 2000.
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study(title="Currency Index USD", shorttitle="Currency Index USD")
Start_USDEUR = input(0.9930, minval=0)
Start_USDCHF = input(1.5902, minval=0)
Start_USDGBP = input(0.6182, minval=0)
Start_USDJPY = input(102.21, minval=0)
Start_USDAUD = input(1.5237, minval=0)
Start_USDCAD = input(1.4455, minval=0)
Start_USDNZD = input(1.9113, minval=0)
USDEUR =  (1 / security("EURUSD",period, close) * 100) / Start_USDEUR
USDCHF = (security("USDCHF",period, close) * 100) / Start_USDCHF
USDGBP =  (1 / security("GBPUSD",period, close) * 100) / Start_USDGBP
USDJPY = (security("USDJPY",period, close) * 100) / Start_USDJPY
USDAUD =  (1 / security("AUDUSD",period, close) * 100) / Start_USDAUD
USDCAD = (security("USDCAD",period, close) * 100) / Start_USDCAD
USDNZD  = (1 / security("NZDUSD",period, close) * 100) / Start_USDNZD
CurSum = (abs(USDEUR) + abs(USDCHF) + abs(USDGBP) + abs(USDJPY) + abs(USDAUD) + abs(USDCAD) + abs(USDNZD)) / 7
nRes = 100 - CurSum
plot(nRes, color=blue, title="Currency Index USD")