Hanoi has a population of approximately 6.5 million residents which has grown exponentially since the turn of the millennium. Most residents of Hanoi have been there for three generations or more and 85% of Hanoi's Population comprises of ethnic Vietnamese. 3% of Hanoi's Population is ethnic Chinese or Khmer and there are members of more than 55 different ethnic groups who call this city home. It is a cultural norm in Hanoi to make conversation with strangers, and tourists are often asked general questions about where they are from or what they do. Such friendliness often proves extremely useful; particularly in cases of street crime where other young male pedestrians might try to catch the culprit while female pedestrians help the victim by calling the police or the ambulance if the victim is wounded.