In the Northern Territory, the Aboriginal and Torres Strait Islander infant mortality rate was over three times as high as the non-Indigenous infant mortality rate (13.6 deaths per 1,000 live births compared with 3.8 deaths per 1,000 live births). Male Aboriginal and Torres Strait Islander infant mortality in the Northern Territory was about 15 deaths per 1,000 live births, while female Aboriginal and Torres Strait Islander infant mortality was 12 deaths per 1,000. For non-Indigenous males the rate was 4.4 deaths per 1,000 births and for females it was 3.3 deaths per 1,000 (ABS 2009b). Between 1998 and 2008 the Indigenous to non-Indigenous rate ratio (the Aboriginal and Torres Strait Islander rate divided by the rate for other Australians) for infant mortality declined in the Northern Territory an average of 1.7% per year, while the rate difference (the Aboriginal and Torres Strait Islander rate minus the rate for other Australians) almost halved from 18.1 to 9.8 deaths per 1,000 births, which suggests that the gap between Aboriginal and Torres Strait Islander and non-Indigenous infant mortality in the Northern Territory has reduced (ABS 2009b). Indigenous Australians have a higher rate of Invasive pneumococcal disease (IPD) than the wider Australian population. In Western Australia between 1997–2007, the IPD incidence rate was 47 cases per 100,000 population per year among Aboriginal people and 7 cases per 100,000 population per year in non-Aboriginal people. After the introduction of a pneumococcal conjugate vaccine (7vPCV), total IPD rates among Aboriginal children decreased by 46% for those less than 2 years of age and by 40% for those 2–4 years of age. Rates decreased by 64% and 51% in equivalent age groups for non-Aboriginal children. Until the 1980s Aboriginal children were recognised as having better oral health than non-Aboriginal children. Today, average rates of tooth decay in Aboriginal children are twice as high as non-Aboriginal children. Between 1991 and 2001, the rate of tooth decay amongst Aboriginal children living in metropolitan areas fell, going against the increase in child tooth decay in remote areas. A study performed in 2001-2002 showed that Indigenous Australian patients showed a higher ratio of missing or decayed teeth than European patients, but a lower ratio of filled teeth. A 2003 study found that complete loss of all natural teeth was higher for Aboriginal people of all age groups (16.2%) compared to non-Aboriginal people (10.2%).