Why is it economical to use high voltages for the transmission of electrical power?

Followings are few reasons.

1. At high voltage for the same power, value of current will be less.

2.If less current in line then less transmission loss(IR2) will occur,which will again save money.

3.If the current will be less then less size of conductor will be required and will save money.

4.If less size then less weight and less strength of poles will be required which will again save money.

I hope will these reasons you can understand the fact.