volumes of sales in these suburbs, and (over time) the huge variations in the numbers of sales in a suburb in a quarter, statistical analysis of "the most expensive suburb" is unreliable; the suburbs appearing in the "top 10 most expensive suburbs this quarter" list is constantly varying. Quarterly Reports for the last two years can be found on the REISA website. Education and research Education forms an increasingly important part of the city's economy, with the South Australian Government and educational institutions attempting to position Adelaide as "Australia's education hub" and marketing it as a "Learning City." The number of international students studying in Adelaide has increased rapidly in recent years to 30,726 in 2015, of which 1,824 were secondary school students. In addition to the city's existing institutions, foreign institutions have been attracted to set up campuses to increase its attractiveness as an education hub. Adelaide is the birthplace of three Nobel laureates, more than any other Australian city: physicist William Lawrence Bragg and pathologists Howard Florey and Robin Warren, all of whom completed secondary and tertiary education at St Peter's College and the University of Adelaide. Primary and secondary education At the level of primary and secondary education, there are two systems of school education. There is a public system operated by the South Australian Government and a private system of independent and Catholic schools. South Australian schools provide education under the Australian Curriculum for reception to Year 10 students. In Years 10 to 12, students study for the South Australian Certificate of Education (SACE). They have the option of incorporating vocational education and training (VET) courses or a flexible learning option (FLO). South Australia also has 24 schools that use International Baccalaureate programs as an alternative to the Australian Curriculum or SACE. These programs include the IB Primary Years Programme, the IB Middle Years Programme, and the IB Diploma Programme. For South Australian students who cannot attend a traditional school, including students who live in rural or remote areas, the state government runs the Open Access College (OAC), which provides virtual teaching. The OAC has a campus in Marden which caters to students from reception to Year 12 and adults who haven't been able to complete their SACE. Guardians are also able to apply for their child to be educated from home as long as they provide an education program which meets the same requirements as