This contrasts with the debate of the early 1990s, when the rise in the average wage of the newly industrializing economies (NIEs) relative to that of the United States was used to allay fears about the effect of trade on income inequality. This may be partly due to a declining growth in labour supply and restrictions on geographical labour mobility (TDR 2010, chap. Moreover, the new labour contract law, which came into effect in 2008, stipulates minimum wage requirements and allows a strengthening of the bargaining power of employees.9 Finally, labour compensation has also increased because of rapidly rising labour productivity. According to Banister and Cook (2011), labour productivity in China's industrial sector (including manufacturing, as well as construction, mining and utilities) increased at an average annual rate of about 10 per cent betw een 1991 and 2008. The reason for this rapid productivity growth is a combination of sizeable and growing capital investment and improved education and skill levels of Chinese workers, along with the use of advanced technologies by transnational corporations (TNCs) engaged in international production sharing, as discussed below .