<Tr> <Td> KS4 </Td> <Td> Year 10 </Td> <Td> 14 - 15 </Td> <Td> Upper school </Td> <Td> Senior </Td> </Tr> <Tr> <Td> Year 11 </Td> <Td> GCSE </Td> <Td> 15 - 16 </Td> </Tr> <Tr> <Td> KS5 </Td> <Td> Year 12 </Td> <Td> None, though individual schools may set end of year tests . </Td> <Td> 16 - 17 </Td> <Td> College </Td> <Td_colspan="2"> Sixth form </Td> </Tr> <Tr> <Td> Year 13 </Td> <Td> A-Levels </Td> <Td> 17 - 18 </Td> </Tr>

How many years are there in high school uk