What was the population in Puerto Rico 10 years ago?

The global population in 1999 was about 6 billion (more precisely 5,978,000,000).

More information on other nations and other parts of the world can be found at the following link: http://www.un.org/esa/population/publications/sixbillion/sixbilpart1.pdf

It directs you to a United Nations (UN) report. It is only 11 pages and worth checking out.