Shenzhen is a major city in Guangdong Province, China. It forms part of the Pearl River Delta megalopolis. The city is located immediately north of Hong Kong Special Administrative Region and holds sub-provincial administrative status, with powers slightly less than a province.Shenzhen was a market town of 30,000[better source needed] people on the route of the Kowloon–Canton Railway. That changed in 1979 when Shenzhen was promoted to city-status and in 1980 designated China’s first Special Economic Zone (SEZ).Official statistics based on China 2010 Census put Shenzhen's total population of 10,357,938, that included migrants staying at least six months.New outlets speculate that these statistics do not include migrant workers. Such estimates put the instantaneous or sum total of individuals who have spend majority of their day in Shenzhen to at least 18 million.Shenzhen was one of the fastest-growing cities in the world during the 1990s and the 2000s.A nationwide 2015 intercensal survey (mini-census conducted five years after the official census in every decade) surveyed for every city in the country recorded 11.389 million residents (9.186 million holding city residency (hukou), the remainder are considered migratory who were present at least six months of the year), while the household size increased to 2.49 people from 2.11 in 2010, indicative of soaring rents.Those not present six months of the year were not tallied.Shenzhen's modern cityscape is the result of its vibrant economy made possible by rapid foreign investment since the institution of the policy of "reform and opening" in late 1979 when the SEZ was established.Shenzhen is a major financial center in southern China. The city is home to the Shenzhen Stock Exchange as well as the headquarters of numerous home grown multinational well-known companies such as Vanke, JXD, Hytera, CIMC, Shenzhen Airlines, Nepstar, Hasee, Ping An Bank, Ping An Insurance, China Merchants Bank, Tencent, ZTE, Huawei and BYD.Shenzhen ranks 22nd in the 2017 edition of the Global Financial Centres Index published by the Z/Yen Group and Qatar Financial Centre Authority.It also has one of the busiest container ports in the world.