After World War I, the population of Paris first reached 3 million inhabitants. The war was over, and many people were moving to the city in order to have access to merchants and various goods that were hard to find elsewhere in the country. The city began to bustle shortly after the war and was one of the first parts of France that began to recuperate. For the rest of the 20th century, the population began to decline slightly, and by the 1960s, it fell dramatically to 2.2 million people. During this time period, other large cities around the world including London and New York City also saw a major decrease in their populations. At the beginning of the 21st century, France's population began to rise again, and between 1999 and 2009, there was a consistent growth of approximately 100,000 people per year. This is due to the large amount of people aged 18-40 living in the area that had children.