Adding that ability will set you back $US 199 per year per website.
The next best, and free, is a country lookup which will add an extra query to your website. There is still a free database which can lookup country/city but it is now so wayout of date and becoming more useless every day.
Alternatively, a small icon could be added which could be clicked to provide that info using the dnsstuff link, though I'm not sure how they would feel about it dnsstuff.com wrote
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