"Weightage" is a commonly used word in India. I'd think, by the extensive usage (both written and oral; casual, professional and academic) this is a legitimate English word in India.

This word refers to the importance of some item that is one of the components of a whole.
http://forum.wordreference.com/showthread.php?t=40668

Example usage:
"He gives way too much weightage to looks, when it comes to girls"
"The mid-semester exams carry 30% of weightage"
"When you hire someone, do you give any weightage at all to past experience?"

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Note added at 1 hr (2009-06-23 10:53:42 GMT)
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you are using "earned value" to define Weightage, as I see above. I think it can't be used as a "translation" as well.