At the beginning of the occupation, almost two-thirds of Dutch Jews - 80,000 of 140,000 - resided within the city of Amsterdam. The majority lived in the central southeast, in adjoining neighborhoods collectively known as the Jewish Quarter. In May 1941, the municipality aided the Nazis by preparing a map detailing concentrations of Jewish inhabitants, which was used to organize arrests and deportations. Each black dot represents ten Jews, so the map became known as the ‘dots map’. The city also provided maps locating Jewish-owned businesses. These act of official collaboration significantly contributed to the unparalleled death toll for the city's Jewish population, where more than 75% were killed in the Holocaust.