I did a quick run through some stats on ESPN. Since 2002 (as far back as they have these stats) the Chicago Cubs have averaged a 15th place record in the majors at the end of each season. In the same span they have averaged the 2nd highest attendance record by percentage of sell-out, behind the Boston Red Sox.
I find it interesting that a team which has not won a World Series Championship since 1908 and has had some rough years still consistently sells out. In this 8 year span the Cubs sold out 95.7% of the 648 regular season games, behind the Red Sox staggering 99.8% sell out rate. What is most surprising...
In the 2004 and 2005 seasons the Cubs finished 3rd and 4th place in the division respectively. Despite these seasons which ended in September they had the highest attendance by percentage in baseball both years.
I was able to live in Wrigleyville for a month in the summer of 2008 and fell in love with the Cubs. I was a baseball fan but never really had a team. I think the Cubs may very well have the best fanbase in professional sports. Anyone care to argue a better fanbase out there in pro sports?