<Tr> <Th> 2004--05 </Th> <Td> Chelsea </Td> <Td> Arsenal Manchester United Everton Liverpool </Td> <Td> Bolton Wanderers Middlesbrough </Td> <Td> Crystal Palace Norwich City Southampton </Td> <Td> Sunderland Wigan Athletic West Ham United </Td> <Td> Henry, Thierry Thierry Henry </Td> <Td> 25 </Td> </Tr> <Tr> <Th> 2005--06 </Th> <Td> Chelsea </Td> <Td> Manchester United Liverpool Arsenal </Td> <Td> Tottenham Hotspur Blackburn Rovers </Td> <Td> Birmingham City West Bromwich Albion Sunderland </Td> <Td> Reading Sheffield United Watford </Td> <Td> Henry, Thierry Thierry Henry </Td> <Td> 27 </Td> </Tr> <Tr> <Th> 2006--07 </Th> <Td> Manchester United </Td> <Td> Chelsea Liverpool Arsenal </Td> <Td> Tottenham Hotspur Everton Bolton Wanderers </Td> <Td> Sheffield United Charlton Athletic Watford </Td> <Td> Sunderland Birmingham City Derby County </Td> <Td> Drogba, Didier Didier Drogba </Td> <Td> 20 </Td> </Tr> <Tr> <Th> 2007--08 </Th> <Td> Manchester United </Td> <Td> Chelsea Arsenal Liverpool </Td> <Td> Everton </Td> <Td> Reading Birmingham City Derby County </Td> <Td> West Bromwich Albion Stoke City Hull City </Td> <Td> Ronaldo, Cristiano Cristiano Ronaldo </Td> <Td> 31 </Td> </Tr>

When did the premier league change to 38 games