Nearly 70 percent of countries worldwide have seen their populations double since 1960, with the global population now exceeding eight billion. India has overtaken China as the most populous nation, while countries like the United Arab Emirates and Qatar have experienced the largest percentage increases in population. In contrast, eight countries, including Bulgaria, have seen their populations decline. Despite overall growth, many nations are facing record-low birth rates, prompting concerns about future economic and social stability. Projections suggest that by 2100, nearly half of all countries will experience population decline, while some African and Middle Eastern countries are expected to see significant growth.