http://www.roymorgan.com/news/press-releases/2007/664/
From Roymorgan Research
The Brisbane Broncos are once again the NRL’s most popular team with an estimated 1,471,000 supporters (up 4,000 from December 2005), according to the latest Roy Morgan Research Single Source data.
The big mover on the NRL supporter “ladder†is the Melbourne Storm who, despite being beaten in the 2006 Grand Final by the Broncos, gained the most supporters (178,000) since December 2005 to be clearly second with 732,000 supporters.
Despite missing the finals in 2006, the North Queensland Cowboys’ supporter base increased by 36,000 to 539,000  moving into third place. The Cowboys have experienced the most rapid growth over the past five years, increasing 349% from 120,000 supporters in 2001.
In fourth place the St George-Illawarra Dragons supporter base increased 11,000 to 531,000, and in fifth place the Wests Tigers saw an increase of 2,000 to 513,000.
The Newcastle Knights enjoyed a solid 2006 season, finishing in fourth position before being ousted by the Broncos in the Semi-Finals. The Knights enjoyed a 5.2% surge in supporters since December 2005, up 24,000 to 486,000.
The biggest losers on the supporter “ladder†are the Sydney Roosters (down 106,000 to 306,000), the Bulldogs (down 79,000 to 395,000) and the Penrith Panthers (down 26,000 to 201,000).
The Cronulla Sharks are the lowest ranking NRL team in terms of number of supporters. Supporter numbers for the Sharks fell 15,000 to 193,000 (down 7.2%).
Overall, the number of NRL supporters increased by 12,000 to 6,175,000 (up 0.2%).
And there is more  Roy Morgan Research Single Source data can be used to highlight some interesting aspects of NRL supporters.
For example, when compared to all NRL supporters, Storm supporters are 79% more likely to have made a purchase from JB Hi-Fi in the last four weeks, Sea Eagles supporters are 40% more likely to agree “I always read the business section of the paper†and Broncos supporters are 20% more likely to have made a purchase from Mitre 10 in the last four weeks. Further details can be found below.