I've found some interesting data about demography in NYC here. The city is largely distinct of any other city of USA in its ethnicity, that makes it a big puzzle of mainly nations in the world.
I will let the census speak for itself, thou.
44% of the population was white.
25.3% of the population was black or African American,
11.6% was Asian
0.4% were American Indian.
17% belonged to some other race
1.6% of New Yorkers belonged to more than one race.
The New York City metropolitan area is home to the largest Jewish community outside Israel.In 2002, an estimated 972,000 Ashkenazic Jews lived in New York City and constituted about 12% of the city's population.The Jewish presence in New York City dates to the 1600s when a Jewish community relocated from Recife seeking freedom of worship (ops!).
As of the 2000 census 255,536 New Yorkers reported German ancestry.
As of the 2000 census 213,447 New Yorkers reported Polish ancestry.
The Romanian community of New York is the largest in United States and North America, with unofficial figures showing 200,000 Romanians in New York.
It is also home to nearly a quarter of the nation's South Asians, approximately 275,000 persons from India (226,587), Pakistan (34,310), Bangladesh (18,825), and Sri Lanka (1,094), and comprise a combined 3.5% of New York City's population.
The largest African American community of any city in the country, at over 2 million within the city's boundaries.
NYC has about 800,000 Puerto Ricans and has the largest Puerto Rican population outside of Puerto Rico.
Another historically significant ethnic group are Italians, who emigrated to the city in large numbers in the early twentieth century, New York City is home to the largest Italian population in the US. New York metropolitan area is home to 3,372,512 Italians, which is the third largest concentration in the world after Milan and Rome metropolitan areas.
The Irish also have a notable presence; one in 50 New Yorkers of European origin carry a distinctive genetic signature on their Y chromosomes inherited from Niall of the Nine Hostages, an Irish high king of the fifth century A.D.
As of the 2000 census 420,810 New Yorkers reported Irish ancestry.