Well it depends on your preferences if your talking about Google Adwords. You can have 100% of your clickers from India if you want- specify that as the only location that you want visitors from. Or 0% if you specify no visitors from india... as overall percentage on run of network, well that would depend on what you were advertising
% of clicks from specific country depend on lot of factors,as others said,u can customize your ads to display in certain countries only.