Nearly half of the global population of 8.2 billion live in cities across the world today, according to a UN report released Tuesday.The World Urbanization Prospects 2025: Summary of Results showed that the world has become increasingly urban, with the number of people living in cities having more than doubled to 45 percent since 1950, when only 20 percent of the world's 2.5 billion people lived in cities.The number of megacities, urban areas with 10 million or more inhabitants, has quadrupled from eight in 1975 to 33 in 2025, with 19 of them located in Asia.The report, released by the...