If Secretary of State Matt Dunlap’s prediction holds true, only about 20 percent of Maine voters will either show up at the polls today or vote absentee in this year’s primaries and referendum balloting.

That’s in contrast to Mainers’ behavior in general elections, where the state consistently ranks among the highest in the nation in percentage of eligible voters casting ballots.

In some years, more than three-quarters of eligible voters cast ballots in presidential elections in November.

Part of the lack of participation may be structural: If you’re not registered in a party, you can’t vote in that party’s primaries.

But many people could well have an interest in a primary vote, because of the fact that Mainers will be picking a new governor this year, the most significant state post affecting Maine’s future.

Given that, while it is too late under state law to switch parties if you are enrolled in one, unenrolled voters — “independents” — can register with a party right at the polls and then unenroll again three months down the road.

And all voters can cast ballots on local issues and the statewide referendum ballot, which not only includes four significant bond issues but an up-or-down vote on Question 1, an effort to repeal a law that would make major changes in the state’s tax code.

In that context, note that, as of as of June 1, independents made up the largest voting bloc among Maine registered voters, with 385,388.

Democrats are next with 329,610. Republicans have 270,601 and Green Independents 34,398.

Too many people around the world would love to have the opportunity that, if Dunlap’s forecast is right, 80 percent of us may ignore today.

So there’s no reason not to vote, and at least five very good reasons — the ballot questions — to make the effort.