Wikipedia has season stats per conference:
https://en.wikipedia.org/wiki/2022_Big_T...all_season
The Big Three each have "over 100%" capacity and an average attendance per game of over 100,000.
Nebraska is "over 100%" and their average attendance per game is 86,732.
Wisconsin's average is next with 73,898 but they are "only" at 92% attendance for the season.
Illinois fans are slow to catch on. Their average per game is just 42,294, third from the bottom, just 69.7% of capacity. They did draw 56,092 to their last game. If you compare to 2021 Illinois is way up. Last year they had just 35,347, 58.3% capacity for the season. It may be a "Big Four" when it comes to the CFP rankings from the Big Ten, but when it comes to attendance it's really just the Big Three (or it's Big Four and Nebraska's the fourth). I like where Bret Bielema has Illinois going but it will take longer for Illinois fans to believe in their football program and it's not a coincidence that Illinois hasn't played any of the Big Three this season.
Maryland is also pretty bad, 2nd to last in the Big Ten. Dead last? Duh. Northwestern at 29,287, 62.1% of capacity, but what do you expect for a 1 win team? Surprised Rutgers isn't "that" bad. 50,772, 96.8% capacity. They had 47,621 fans for a game vs. WAGNER.