Bulgaria becomes the 21st country to switch to the euro as it enters the New Year, a milestone met with both cheers and fears, nearly 20 years after the Balkan nation joined the European Union. Successive governments have advocated joining the euro, hoping that it will boost the economy of the bloc's poorest member. But Bulgarians have long been divided over the switch, with many worrying the introduction could usher in higher prices and add to the political instability rattling the country.