from Carrall Street to Heatley Avenue, at least 60% of units must be dedicated to social housing and the rest must be rental units. Rents in at least one-third of new social housing units are not permitted to exceed the shelter component of welfare rates. Proponents say that new developments revitalize the area, improve the quality of life, provide new social housing, and encourage a stronger retail environment and a stabilizing street presence. They emphasize that their goal is for the DTES to include a mixture of income levels and avoid the problems associated with concentrated poverty, not to become an expensive yuppie-oriented neighbourhood like nearby Yaletown. Others oppose the addition of market housing and upscale businesses to the DTES, in the belief that these changes will drive up prices, displace low-income residents, and make poor people feel less at home. Protests against new businesses and housing developments have occasionally turned violent. Strategies Housing strategies Although housing and homelessness are often perceived as being municipal issues, social housing is traditionally funded primarily by senior levels of government, which receive 92% of tax revenue in Canada. Libby Davies, a former DTES activist and Member of Parliament, called for a National Housing Strategy in 2009, saying that Canada is the world's only industrialized country with no national housing plan. In 2014, the City of Vancouver approved a 30-year plan for the greater DTES area. It sets out a goal of having 4,400 units of social housing added to the greater DTES area, 3,350 units of social housing added elsewhere in the city, and 1,900 units of new supportive housing scattered throughout the city. The cost of implementing the plan is estimated at $1 billion, of which $220-million would be paid by the city, $300-million by developers, and more than $500-million from the provincial and/or national governments. The provincial government, which recently invested $300 million in social housing in Vancouver, said that it will not be funding the proposed housing expansion, and that its housing strategy had shifted towards other models such as rent assistance rather than construction. Addiction and mental illness strategies In 2001, the city adopted a "Four Pillars" drug strategy consisting of four equally important "pillars": prevention, treatment, enforcement, and harm reduction. Advocates of the Four Pillars strategy say that the 36 recommendations associated with the policy have only been partly implemented, with prevention, treatment, and harm reduction all being