In Finland, like the rest of the Nordics, Liverpool's support is down to their success from the mid-70s to late 80s. Finnish TV, like in Norway, Sweden...used to show one English game each weekend, typically the main game that Match of the Day would be featuring that evening as the cameras would be there anyway. As Liverpool were winning things, they were usually on Match of the Day as the main game. So, if you were a young football fan in Finland the only game you watched each week was 75% or more likely to be a Liverpool one.
Remember back then that this was probably the only way to get to know/support a team, aside from 2 day old results and match reports in a foreign paper so it stands to reason that Liverpool drew all the support.