From the wind-swept coasts of Victoria and Tasmania to the picturesque harbours of New South Wales, the tropical islands and Great Barrier Reef of Queensland to the huge shallow bays of the Northern Territory, Australia has it all. Although human habitation of Australia is estimated to have begun around 45 000 years ago, modern Australia is considered a European colony since the 17th. century and became an independant country - member of the Commonwealth - since 1901. It is a prosperous developed country, the world's thirteenth largest economy. Australia ranks highly in many international comparisons of national performance such as human development, quality of life, health care, life expectancy, public education, economic freedom and the protection of civil liberties and political rights The country has been referred to colloquially as Oz since the early 20th. century and Aussie is a common, colloquial term for "Australian".