Dear- I heard that Russia+Brazil+Benesuela give 8% for the national debt. and China give roughly 4%. Where would I find the link for comparison, to search for country with big interest?
Try this https://www.dukascopy.com/swiss/english/marketwatch/calendars/InterestRatesCalendar/ Ukraine is 30% wow....
Just be aware that generally speaking sovereign debt is denominated in the country's domestic currency. Currency fluctuations will be a much greater driver of your returns than interest. The minimum you should do is look at real interest rates (i.e. adjusted for inflation)
Brazil's is 14,25%. It's called SELIC if you wanna look it up. Links: http://www.bcb.gov.br/?INTEREST https://www.bcb.gov.br/?INFLATION https://www.bcb.gov.br/?RED-FOCUSREPORT