paragraph_text: Tourism has been a key factor in economic development for many Southeast Asian countries, especially Cambodia. According to UNESCO, "tourism, if correctly conceived, can be a tremendous development tool and an effective means of preserving the cultural diversity of our planet." Since the early 1990s, "even the non-ASEAN nations such as Cambodia, Laos, Vietnam and Burma, where the income derived from tourism is low, are attempting to expand their own tourism industries." In 1995, Singapore was the regional leader in tourism receipts relative to GDP at over 8%. By 1998, those receipts had dropped to less than 6% of GDP while Thailand and Lao PDR increased receipts to over 7%. Since 2000, Cambodia has surpassed all other ASEAN countries and generated almost 15% of its GDP from tourism in 2006.

paragraph_text: During the Eocene (56 million years ago - 33.9 million years ago), the continents continued to drift toward their present positions. At the beginning of the period, Australia and Antarctica remained connected, and warm equatorial currents mixed with colder Antarctic waters, distributing the heat around the world and keeping global temperatures high. But when Australia split from the southern continent around 45 Ma, the warm equatorial currents were deflected away from Antarctica, and an isolated cold water channel developed between the two continents. The Antarctic region cooled down, and the ocean surrounding Antarctica began to freeze, sending cold water and ice floes north, reinforcing the cooling. The present pattern of ice ages began about 40 million years ago.[citation needed]

paragraph_text: A continent is one of several very large landmasses on Earth. Generally identified by convention rather than any strict criteria, up to seven regions are commonly regarded as continents. Ordered from largest in size to smallest, they are: Asia, Africa, North America, South America, Antarctica, Europe, and Australia.

paragraph_text: Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans. The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics.

paragraph_text: Sid Myer is an Australian businessman and philanthropist with strong associations with ongoing relations between Australia and Asia. He is a grandson of Sidney Myer and Dame Merlyn Myer. Since graduating from Monash University with a Bachelor of Economics and a Graduate Diploma of Marketing, Myer has been exposed to over 25 years of business experience.

paragraph_text: Yellowstone National Park spans an area of 3,468.4 square miles (8,983 km), comprising lakes, canyons, rivers and mountain ranges. Yellowstone Lake is one of the largest high - elevation lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent. The caldera is considered an active volcano. It has erupted with tremendous force several times in the last two million years. Half of the world's geothermal features are in Yellowstone, fueled by this ongoing volcanism. Lava flows and rocks from volcanic eruptions cover most of the land area of Yellowstone. The park is the centerpiece of the Greater Yellowstone Ecosystem, the largest remaining nearly - intact ecosystem in the Earth's northern temperate zone. In 1978, Yellowstone was named a UNESCO World Heritage Site.

paragraph_text: Small-scale "expedition tourism" has existed since 1957 and is currently subject to Antarctic Treaty and Environmental Protocol provisions, but in effect self-regulated by the International Association of Antarctica Tour Operators (IAATO). Not all vessels associated with Antarctic tourism are members of IAATO, but IAATO members account for 95% of the tourist activity. Travel is largely by small or medium ship, focusing on specific scenic locations with accessible concentrations of iconic wildlife. A total of 37,506 tourists visited during the 2006–07 Austral summer with nearly all of them coming from commercial ships. The number was predicted to increase to over 80,000 by 2010.

paragraph_text: The Southern Ocean, geologically the youngest of the oceans, was formed when Antarctica and South America moved apart, opening the Drake Passage, roughly 30 million years ago. The separation of the continents allowed the formation of the Antarctic Circumpolar Current.

paragraph_text: Since then, he has published a summary of the history of geology in Canada, and short biographies of Canadian geologists. Another Canadian geologist Joseph William Winthrop Spencer (1851–1921; born in Dundas, ON) was the subject of a more extensive study. He has also published historical studies of geologists elected the Royal Society of Canada during its first fifty years, and the history of the earth sciences during the twentieth century. During the last five years he has studied the source of the stone used for building in nineteenth-century southern Ontario.

paragraph_text: The Paleozoic spanned from roughly 541 to 252 million years ago (Ma) and is subdivided into six geologic periods; from oldest to youngest they are the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Geologically, the Paleozoic starts shortly after the breakup of a supercontinent called Pannotia and at the end of a global ice age. Throughout the early Paleozoic, the Earth's landmass was broken up into a substantial number of relatively small continents. Toward the end of the era the continents gathered together into a supercontinent called Pangaea, which included most of the Earth's land area.

paragraph_text: Since then, tourism in Nepal has thrived; it is the country's most important industry.[citation needed] Tourism is a major source of income for most of the people in the city, with several hundred thousand visitors annually. Hindu and Buddhist pilgrims from all over the world visit Kathmandu's religious sites such as Pashupatinath, Swayambhunath, Boudhanath and Budhanilkantha. From a mere 6,179 tourists in 1961/62, the number jumped to 491,504 in 1999/2000. Following the end of the Maoist insurgency, there was a significant rise of 509,956 tourist arrivals in 2009. Since then, tourism has improved as the country turned into a Democratic Republic. In economic terms, the foreign exchange registered 3.8% of the GDP in 1995/96 but then started declining[why?]. The high level of tourism is attributed to the natural grandeur of the Himalayas and the rich cultural heritage of the country.

paragraph_text: The Ordovician Period started at a major extinction event called the Cambrian-Ordovician extinction events some time about 485.4 ± 1.9 Ma. During the Ordovician the southern continents were collected into a single continent called Gondwana. Gondwana started the period in the equatorial latitudes and, as the period progressed, drifted toward the South Pole. Early in the Ordovician the continents Laurentia, Siberia and Baltica were still independent continents (since the break-up of the supercontinent Pannotia earlier), but Baltica began to move toward Laurentia later in the period, causing the Iapetus Ocean to shrink between them. Also, Avalonia broke free from Gondwana and began to head north toward Laurentia. The Rheic Ocean was formed as a result of this. By the end of the period, Gondwana had neared or approached the pole and was largely glaciated.

paragraph_text: Continental drift is the movement of the Earth's continents relative to each other, thus appearing to ``drift ''across the ocean bed. The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected by some for lack of a mechanism (though this was supplied later by Arthur Holmes). The idea of continental drift has been subsumed by the theory of plate tectonics, which explains how the continents move.

paragraph_text: Southern California's economy is diverse and one of the largest in the United States. It is dominated and heavily dependent upon abundance of petroleum, as opposed to other regions where automobiles not nearly as dominant, the vast majority of transport runs on this fuel. Southern California is famous for tourism and Hollywood (film, television, and music). Other industries include software, automotive, ports, finance, tourism, biomedical, and regional logistics. The region was a leader in the housing bubble 2001–2007, and has been heavily impacted by the housing crash.

paragraph_text: Africa is the world's second largest and second most - populous continent (behind Asia in both categories). At about 30.3 million km (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, the Isthmus of Suez and the Red Sea to the northeast, the Indian Ocean to the southeast and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagos. It contains 54 fully recognised sovereign states (countries), nine territories and two de facto independent states with limited or no recognition. The majority of the continent and its countries are in the Northern Hemisphere, with a substantial portion and number of countries in the Southern Hemisphere.

paragraph_text: Positioned asymmetrically around the South Pole and largely south of the Antarctic Circle, Antarctica is the southernmost continent and is surrounded by the Southern Ocean; alternatively, it may be considered to be surrounded by the southern Pacific, Atlantic, and Indian Oceans, or by the southern waters of the World Ocean. It covers more than 14,000,000 km2 (5,400,000 sq mi), making it the fifth-largest continent, about 1.3 times as large as Europe. The coastline measures 17,968 km (11,165 mi) and is mostly characterized by ice formations, as the following table shows:

paragraph_text: Tourism is an important component of the Puerto Rican economy supplying an approximate $1.8 billion USD per year. In 1999, an estimated five million tourists visited the island, most from the United States. Nearly a third of these were cruise ship passengers. An increase in hotel registrations, which has been observed since 1998, and the construction of new hotels and the Puerto Rico Convention Center are indicators of the current strength of the tourism industry. In 2009, tourism accounted for nearly 7% of the islands' gross national product.

paragraph_text: Since 7500 yr ago, a situation with tides and currents, very similar to present has existed. Rates of sea-level rise had dropped so far, that natural sedimentation by the Rhine and coastal processes together, could compensate the transgression by the sea; in the last 7000 years, the coast line was roughly at the same location. In the southern North Sea, due to ongoing tectonic subsidence, the sea level is still rising, at the rate of about 1–3 cm (0.39–1.18 in) per century (1 metre or 39 inches in last 3000 years).

paragraph_text: The Earth of the early Archean (4,000 to 2,500 million years ago) may have had a different tectonic style. During this time, the Earth's crust cooled enough that rocks and continental plates began to form. Some scientists think because the Earth was hotter, that plate tectonic activity was more vigorous than it is today, resulting in a much greater rate of recycling of crustal material. This may have prevented cratonisation and continent formation until the mantle cooled and convection slowed down. Others argue that the subcontinental lithospheric mantle is too buoyant to subduct and that the lack of Archean rocks is a function of erosion and subsequent tectonic events.

paragraph_text: Antarctica (US English i/æntˈɑːrktɪkə/, UK English /ænˈtɑːktɪkə/ or /ænˈtɑːtɪkə/ or /ænˈɑːtɪkə/)[Note 1] is Earth's southernmost continent, containing the geographic South Pole. It is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometres (5,400,000 square miles), it is the fifth-largest continent in area after Asia, Africa, North America, and South America. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km (1.2 mi; 6,200 ft) in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula.

Question: Since what year has tourism been ongoing to the Earth's southernmost continent?
Answer: 1957