December 18 marks International Migrants Day, observed to highlight the difficulties and contributions of migrants all over the world. According to Global Migration Data Portal, the number of international migrants worldwide reached 272 million in 2019. Female migrants make up 48 percent of the total. Three out of four international migrants are of working age or between 20 and 64 years old. Over 160 million are migrant workers. The United Nations says there are an estimated 33 million migrant children, up from 24 million during 1990 to 2000.