Surprisingly, yes - we wouldn't be absolute top, I don't think, but we're still pretty much there.
Take our top Edinburgh clubs, for example. Hibs (17,826) and Hearts (20,764) have an average attendance of 19,295 every week. Edinburgh's population is 507,170 which, when divided into the average number of football supporters, means that one out of every 26 people get themselves to Easter Road or Tynecastle. In north London, Arsenal (59,364) and Tottenham (70,331 at Wembley) have an average of 64,848 every match, in a city population of 8,787,892. This divides into one supporter in every 136th person.
It's a 4% in Edinburgh to 1% in London comparison.
Now, we understand that there are a HUGE number of variables in those numbers - obviously there are. But as a quick and dirty comparison, it gives you a rough idea of where we're at without bothering to use the Glasgow two. If you use the same numerology principles, it's almost 5% (rounding up from 4.5%) of weegies that go to one of the piggeries each week.
Scottish fans are fanatical.
The snag is that it's hard to drum up sponsorship or TV money when you're offering a product that amounts to "Who are Celtic Going to Beat Up Today?"
[An interesting note, not directly related, is that given the paucity of success Hibs and Hearts have had, their supports are remarkably resilient when compared to Celtic or "Rangers" (whose respective supports collapse when they're poor). This is especially true, given that most other Scottish teams draw their support much more regionally than do the evil twins.]