Crowd trouble club-by-club
Violence at football matches of the kind witnessed outside and inside Upton Park at Tuesday's Carling Cup match between West Ham and Millwall has been thankfully rare in recent years.
But the Home Office keeps a record of every arrest relating to professional football in England and Wales, as well as banning orders handed out to persistent or serious offenders.
Each year, it publishes a club-by-club breakdown of arrests made, including the type of offence, ranging from ticket touting or pitch invasion to violent disorder or possession of a weapon.
So where do each team's supporters rank?
Cardiff and Leeds fans, who clashed in the FA Cup in 2002, fare badly in the statistics
Taking Tuesday's two sets of fans as examples, by November last year, 117 Millwall fans had been given banning orders. Only Leeds United (152) and Cardiff City (136) had more.
West Ham had 39 supporters with banning orders in the same list, in the middle of the table for Premier League clubs, which was headed by Portsmouth with 91.
The last set of figures published covers the 2007/08 season, but the Home Office online archive stretches back at least to 2001. You can download PDF files of the data here:
Statistics on football-related arrests and banning orders 2007-2008
Statistics on football-related arrests and banning orders 2006-2007
Statistics on football-related arrests and banning orders 2005-2006
Statistics on football-related arrests and banning orders 2004-2005
Statistics on football-related arrests and banning orders 2003-2004
Statistics on football-related arrests and banning orders 2002-2003
Statistics on football-related arrests and banning orders 2001-2002
Using all the links, you can see how arrests and banning orders for each team - and for whole divisions, the Football League and the Premier League - have changed so far this century.
For some additional context, there's also a helpful page from the University of Leicester listing figures for arrests at football matches from the 1986/87 season through to 1998/99.
Broadly, the trend shows violence at football matches continues to fall - or at least, arrests do.
In 1988/89 there were just over 6,000 arrests at games in England and Wales. There were 3,842 arrests in 2007/08.
The University of Leicester points out that hooliganism has long been more of a problem outside grounds than inside and the Home Office figures suggest around six in every 10 arrests are made outside the stadium.
But two-thirds of games manage to pass off without a single arrest being made.
It's difficult to draw many conclusions about individual teams without spending time properly analysing the data, but I've pulled out some more info from these files and added it below - add a comment if you find anything else interesting.
In terms of arrests at matches, Manchester United fans were the biggest offenders looking at the raw data, with 248 supporters arrested in 07/08.
That doesn't take into account the club's larger attendances - and dividing by home attendance won't work, since arrest figures include their supporters at away matches (and it's largely away fans causing the trouble), so it's unfair to simply label United fans as the worst-behaved without really crunching the numbers.
Reading and Fulham can both be proud of largely unblemished records in the top flight that season, though, accounting for just 31 arrests between them.
Almost a third of Birmingham fans' 99 arrests were for the serious offence of violent disorder, far more than for any other top-flight team.
Further down the divisions, Cambridge United's figure of 16 arrests stands out in the Conference National, while Chesterfield had the highest number of arrests in League Two.
Leeds fans recorded more arrests than those of any other professional team, with the exception of Manchester United. (Though again, remember their home attendances and away support will have been higher - not that this entirely accounts for the figure of 156 arrests.)
It's interesting that the figure for Leeds has increased by 52 since the 2002/03 season, when Leeds were in the Premier League.
Millwall's figure for arrests has increased from 18 to 78 in that time. One Millwall fan was arrested for a public disorder offence in 2002/03; 40 supporters were arrested for the same offence in 2007/08.
However, when publishing these figures in 2008, the Home Office said the last four years had seen "the lowest number of football-related arrests since records begun".
Is violence at football matches on the way down, despite events at Upton Park, and do all these stats reflect your experiences at matches?