<Tr> <Td_colspan="2"> <Table> <Tr> <Th_colspan="2"> College Football Playoff National Championship </Th> </Tr> <Tr> <Td> <2016 </Td> <Td> 2018> </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Th_colspan="2"> College Football Playoff National Championship </Th> </Tr> <Tr> <Td> <2016 </Td> <Td> 2018> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> College Football Playoff National Championship </Th> </Tr> <Tr> <Td> <2016 </Td> <Td> 2018> </Td> </Tr>

Who won the national college football championship this year