Here is an alarmingly informative October 18, 2005 article from Professor Peter Dreier (key points are italicized below):
The two major homeowner tax breaks cost the federal government almost $90 billion last year—$70.1 billion for the mortgage interest deduction and $19.3 billion for the property tax deduction.
Less than one-fourth of all low-income Americans (those who have Section 8 rental vouchers or who live in government-assisted developments) receive federal housing subsidies. In contrast, almost two-thirds of affluent Americans—many living in mansions—get housing aid from Washington.
More than half (53.7 percent) of last year's $89.5 billion homeowner subsidies went to the 11.8 percent of taxpayers with incomes over $100,000. More than one-fifth (20.6 percent) of these subsidies went to the wealthiest 2.3 percent of taxpayers with incomes over $200,000—some living in mansions.
Wealthy households are most likely to own homes and to itemize deductions. Half of all homeowners do not claim deductions at all.
62 percent of households with incomes above $200,000 receive a homeowner tax break, averaging $7,219. In contrast, only 3.5 percent of households with incomes between $10,000 and $20,000 get any subsidy, averaging $317.
Only one-third of the 52 million households with incomes between $30,000 and $75,000 receive any homeowner subsidy.