According to the U.S. Treasury Department, 4,279 people gave up their U.S. citizenship and green cards in 2015. It is the third consecutive year of record renunciations from America. In 2014, 3,415 people turned in their passports. The Wall Street Journal claims the increase can be attributed to the recent law enforcement campaign against US taxpayers with undeclared offshore accounts.
In addition to unrestricted travel in and out of the US, they also lose government protection, access to federal jobs, and of course their right to vote in US elections. The process of renunciation costs anywhere from $450 to $2350. Based on the estimated U.S. citizenship of 321,368,864, the percentage of Americans renouncing was 0.0013314917776228626%.