Economic and Technological Development Zones (经济技术开发区) were initially established in the open coastal cities during the 80s and then introduced in more regions nationwide to increase regional economic aggregate. There are generally 4 phases of the development of Economic and Technological Development Zones. The start-up phase was from 1984 to 1991, followed by the second phase (1992-1998) when China witnessed the fast expansion of this type of zones. From 1999 to 2002, the development was stable. From 2003 to present, it’s the scientific development period. By the end of 2012, there were 171 national economic and technological development zones. As of September 2015, there were 219 economic and technological development zones, distributed in every province in the mainland China, of which Jiangsu has the most with 26, followed by Zhejiang with 21, and Shandong with 15.