Celebrities and billionares:
That is the lesson from the disclosure that Eduardo Saverin, the
30-year-old billionaire who helped found Facebook, has renounced his
U.S. citizenship to become a resident of Singapore.
Singapore offers huge tax advantages for people like Mr. Saverin,
whose wealth is primarily in the form of capital gains. The Southeast
Asian city-state has no capital-gains tax and its top income-tax rate
is 20%—compared with rates of 15% and 35%, respectively, in the U.S.
[...]
Jet Li became a citizen of Singapore in 2011, and while the kung fu superstar did not say whether he had renounced either his Chinese
or American citizenship, Singapore law forbids dual citizenship.
[...]
The act of expatriating isn't new, whether for tax or other reasons.
Global investing titan John Templeton famously gave up his U.S.
citizenship in the 1960s to become a citizen of the Bahamas, although
his family says it wasn't for tax reasons. Biographers of deceased
director John Huston and the late actor Yul Brynner report
that each gave up his American citizenship in the 1960s.
source: WSJ
See also long list on Wiki: List of former United States citizens who relinquished their nationality
As for numbers:
Rich Americans renouncing U.S. citizenship rose sevenfold since UBS AG
(UBSN) whistle-blower Bradley Birkenfeld triggered a crackdown on tax
evasion four years ago.
About 1,780 expatriates gave up their nationality at U.S. embassies
last year, up from 235 in 2008, according to Andy Sundberg, secretary
of Geneva’s Overseas American Academy, citing figures from the
government’s Federal Register. The embassy in Bern, the Swiss capital,
redeployed staff to clear a backlog as Americans queued to relinquish
their passports.
source: Bloomberg