Of a labor force of 4 million the average Zambian works for 45 hours a week. However, this official figure does not take account of those who work outside of the official sector and embark upon such activities as subsistence farming on small plots of land and petty trading. Zambia has been a member of the International Labour Organisation since independence in 1964, yet it only ratified Conventions 87 (Freedom of Association and Protection of the Right to Organize) and 98 (Right to Organize and Collective Bargaining) as late as 1994. Zambia's trade unions are obliged to join the highly centralized Zambia Congress of Trade Unions (ZCTU). The ZCTU is a very powerful organization and by withdrawing its support from the UNIP in 1990, it almost assured the MMD's electoral success in 1991. Six of 7 ZCTU leaders joined the 1991 MMD government, including President Chiluba who had been the ZCTU's chairman. However, the ZCTU is highly critical of the MMD, in particular its pro-business policies such as the liberalization of the economy which has resulted in a decline of living standards for Zambia's workers. There is also tension within the ZCTU. In 1995 3 of its twenty affiliate trade unions broke away with the intention of setting up a competing center body.