The majority are not Rangers fans either. MORI and Gallup do not exactly do polls on this sort of stuff so there is no way to be scientific about it, but maybe each of them has about 35-40% of the people who follow a team and the rest are shared around all the other clubs. What those of all allegiances are coming to terms with - whether they rejoice in the fact or resent it - is that Celtic have turned the Scottish game into a one-party state.
For most of its history the league title has been an endless tennis rally between Celtic and Rangers, the championship switching from one to the other every year or two. Only now and again has one of them emerged into the clear daylight of a sustained period of dominance. Celtic won six in a row from 1905, Rangers five from 1927. In the late 1960s and early '70s there were times when it looked as if Jock Stein had built a force that would never be caught.
When Rangers emulated Stein's nine consecutive titles - latterly buttressed by the bountiful revenue stream of the Champions League - it felt as if Sir David Murray, Graeme Souness and Walter Smith had moved the Ibrox club to a position of power which would obliterate any competition. And what happened? The Lisbon Lions era was built around Stein's individual genius and when his powers waned Celtic were drawn back into the pack. In the late 1990s Rangers grew old and tired, and misspent their resources, to the point a rebuilt Celtic got back among the titles.
Currently the record books show only two consecutive league wins for Celtic but that is the equivalent of taking a snapshot of Usain Bolt in the early stages of a 100m race. Everyone can be pretty sure of what is coming next. At Tannadice on Saturday there were the latest renditions of a tune that the Celtic support has been singing for quite a while: "Here we go, 10 in a row." It's part-celebration, part-triumphalism, part-threat to you-know-who.
There are 40 clubs which have long grown accustomed to the idea of having no real chance of being Scottish champions any time soon, and one which has a demanding fanbase unused to being denied anything for long. It is common these days to hear people talk about how Celtic have the potential to begin a period of unprecedented domination "if they use their money wisely". What they mean is that if Celtic keep running themselves prudently, employing the right manager and players, staying out of debt and always having money to spend to replenish a winning squad, it is going to take an almighty effort for Rangers to ever catch them.
The apocalyptic scenario for Rangers is that Celtic keep getting into the Champions League group every year. They secured £20m in Uefa money alone last season and now they have another £16m this season. That is almost twice as much dough as Rangers raised from a one-off share issue. If Celtic pull off another two qualifications in 2014 and 2015 that would amount to around £80m washing into the club before Rangers even have the chance to take them on in the league.
Given that all the fundamentals - season-ticket, commercial and sponsorship income - are otherwise broadly comparable between the Glasgow clubs, the long-term difference between them will be Champions League income. And that means that when a player's agent tries to bring a talent to Glasgow (the same player is often offered to both clubs at the same time), Celtic should be able to pay higher transfer fees and wages every time they both want the same man.
All of this is a chilling thought around Ibrox. Horrifying, in fact. The Uefa golden goose that was once Rangers', and then shared, is now exclusively Celtic's. They can thank David Murray and Craig Whyte for that. It used to be the rest of Scottish football that was excluded at one or both of the Old Firm's expense; now Rangers are out in the cold too. Rangers have been in the Champions League group stage 10 times and Celtic are about to play in it for the eighth time.
At a very conservative estimate (Champions League income has grown over the past 20 years) that is about £180m of Uefa money the Old Firm have enjoyed, in addition to their already vastly superior regular income. Last season Motherwell made around £195,000 from Uefa, and Hearts and St Johnstone £75,000 each - a tiny fraction of Celtic's £20m. The champions' excellent campaign also meant £100,000 in "solidarity" payments from Uefa for all other top-flight clubs, but that amounts to (welcome) crumbs. The Champions League embodies the concept of a self-perpetuating elite in which the rich get richer.
When I spoke to a couple of SPFL Premiership club directors about how they reacted to Celtic generating Uefa income on a scale which makes it impossible for them to be given anything more than the odd bloody nose over the course of a season, one said: "It almost doesn't concern us. We're resigned to them always winning the league now and our competition is to finish second. Most clubs are happy for them to get into the group because it means a bit of Uefa money for us. It's probably very different for Rangers."
Every empire falls eventually. The eras of Stein and Souness/Smith came to natural ends. Rosenborg show that even monopolising a country's Champions League access does not guarantee permanent rule. But Celtic's position of strength, and their advantages, are greater than any board of directors have known since Scottish football began.