What percentage of the world's population is Black?

   To answer this question there really isn't a "Black Race" per say. Black is not literally the color of the people commonly referred to as "Black". As a matter of fact "Black" people actually come in different shades of brown."Black" people range from light caramel to nearly black in color. Much of the population of the America's especially the Caribbean nations of Cuba, Haiti's, Dominican republic, Jamaica & others have a large "African" population as well as "African" admixture others like Mexico, Colombia, Venezuela & Brazil  also have extensive "African" admixtures, along with the Middle East & Northern Africa. In many Latin nations dark skinned peoples have down played their "African" genes by using such terms as "Moreno" but rarely do they claim "Black" or "Negro"even with apparent African features.This has to do with the fact when colonial Spain & France ruled over the area light skinned "Blacks"or"Mulattoes" were seen as superior to the "Black" African slave populations & held privileges that weren't available to "Black" Africans slaves many of the "Mulattoes" along with the "White" populous later formed the elites of the newly created Nations of the America's. In Middle Eastern countries along the Red Sea their has been mixing with Africans for centuries especially after the birth of Islam. A large number of Arabs in Saudi Arabia for example have extensive African admixture. The Aksumite empire of what is now Northern Ethiopia ruled large swathes of present day Yemen & portions of Saudi Arabia. Ancient Egyptians were infact "Black" African similar to the Semitic & Cushitic Peoples of present day Ethiopia, Somalia & Horn of Africa in general. The modern Egypt we know today was "Arabized" after the birth of Islam. Also ancient Rome had a substantial "Black" population. The continent of Africa being the traditional  home land of "Black" people is very diverse there are dozens of visible phyno types such as the Yoruba peoples of present day Nigeria which many "Black" Americans share common DNA with. Also the Amhara & Somali's despite their angular faces & sharp features are actually native to Africa these are just a few of the visible phyno types of the African Continent. 

The number of "Black" People world wide can range from 1.5 Billion to 2 Billion depending on who you define as "BlacK" as the term is very subjective most people in the world identify them self's by Ethnicity, Culture, Nationality or even Religious. Only in a few western countries like the U.K and the United States are such terms as "White & Black" used to identify people.