Birth rate
According to the CIA's "The World Factbook", the country with the highest birth rate is Niger at 6.49 children born per woman and the country with the lowest birth rate is Taiwan, at 1.13 children born per woman.
Immigration by country
New Zealand has relatively open immigration policies. 23% of the population was born overseas, mainly in Asia, Oceania, and the United Kingdom, one of the highest rates in the world.