<Table> <Tr> <Th> Years </Th> <Th> Teams </Th> <Th> Byes </Th> <Th> Play - in games </Th> </Tr> <Tr> <Td> 1939--1950 </Td> <Td> 8 </Td> <Td_colspan="2"> </Td> </Tr> <Tr> <Td> 1951--1952 </Td> <Td> 16 </Td> <Td_colspan="2"> </Td> </Tr> <Tr> <Td> 1953--1968 </Td> <Td> 22--25 </Td> <Td> 7--10 </Td> <Td> </Td> </Tr> <Tr> <Td> 1969--1974 </Td> <Td> 25 </Td> <Td> 7 </Td> </Tr> <Tr> <Td> 1975--1978 </Td> <Td> 32 </Td> <Td_colspan="2"> </Td> </Tr> <Tr> <Td> 1979 </Td> <Td> 40 </Td> <Td> 24 </Td> <Td> </Td> </Tr> <Tr> <Td> 1980--1982 </Td> <Td> 48 </Td> <Td> 16 </Td> </Tr> <Tr> <Td> </Td> <Td> 52 </Td> <Td> 16 </Td> <Td> </Td> </Tr> <Tr> <Td> 1984 </Td> <Td> 53 </Td> <Td> 16 </Td> <Td> 5 </Td> </Tr> <Tr> <Td> 1985--2000 </Td> <Td> 64 </Td> <Td_colspan="2"> </Td> </Tr> <Tr> <Td> 2001--2010 </Td> <Td> 65 </Td> <Td> 0 </Td> <Td> </Td> </Tr> <Tr> <Td> 2011--</Td> <Td> 68 </Td> <Td> 0 </Td> <Td> </Td> </Tr> </Table> <Tr> <Th> Years </Th> <Th> Teams </Th> <Th> Byes </Th> <Th> Play - in games </Th> </Tr> <Tr> <Td> 1939--1950 </Td> <Td> 8 </Td> <Td_colspan="2"> </Td> </Tr> <Tr> <Td> 1951--1952 </Td> <Td> 16 </Td> <Td_colspan="2"> </Td> </Tr>

When did all four number one seeds make the final four