at senior schools, mostly called Junior Colleges. [ 192 ] Some schools have a degree of freedom in their curriculum and are known as autonomous schools. These exist from the secondary education level and up. [ 190 ] National examinations are standardised across all schools, with a test taken after each stage. After the first six years of education, students take the Primary School Leaving Examination , [ 188 ] which determines their placement at secondary school. At the end of the secondary stage, GCE "O"-Level exams are taken; at the end of the following pre-university stage, the GCE "A"-Level exams are taken. Of all non-student Singaporeans aged 15 and above, 18% have no education qualifications at all while 45% have the Primary School Leaving Examination as their highest qualification; 15% have the GCE 'O' Level as their highest qualification and 14% have a degree. [ 193 ] Singaporean students consistently rank in the top five in the world in the two major international assessments of mathematics and science knowledge: Health Singapore has a generally efficient healthcare system, even though their health expenditures are relatively low for developed countries. [ 198 ] The World Health Organisation ranks Singapore's healthcare system as 6th overall in the world in its World Health Report . [ 199 ] In general, Singapore has had the lowest infant mortality rate in the world for the past two decades. [ 141 ] Life expectancy in Singapore is 80 for males and 85 for females, placing the