Query: What year's poll of supporters said that the Tottenham rivalry was greatest?
Context: In addition, Arsenal and Manchester United developed a strong on-pitch rivalry in the late 1980s, which intensified in recent years when both clubs were competing for the Premier League title – so much so that a 2003 online poll by the Football Fans Census listed Manchester United as Arsenal's biggest rivals, followed by Tottenham and Chelsea. A 2008 poll listed the Tottenham rivalry as more important.