Collective bargaining mechanisms were first piloted in the mid-1990s and have been evolving ever since. The 2008 landmark Labour Contract Law sets out regulations governing collective contracts. At the same time, tripartite co-ordination bodies have been set up at provincial level (in 2002) as well as at city and prefecture levels. Union membership has also expanded, coinciding with an increasingly tight labour market. While it remained stable at about 100 million throughout the 1990s, union membership has more than doubled during the 2000s to reach 226 million - over a quarter of the labour force - in 2009 (Cai and Wang, 2011). A significant number of countries increased minimum wages in the years before the financial crisis of 2007-08 (ILO, 2009), while others made changes in response to the crisis.