Around the country, election watchers are being stunned by the large numbers of early voters – in Florida, North Carolina, lots of other places.

Not so stunned in Oregon, home of the mail-in early vote as an institutionalized practice. The stats as of today are that about 24% of eligible voters have turned in ballots, compared with 30% four years ago at this point in the process.

Why the lower number, in a year when interest in the election generally seems to be running so high?

At Blue Oregon, Jeff Alworth asked readers for any pet theories about this. To which one reader replied, “Conservative felines in Los Gatos emailed their Oregon counterparts to chew up owners’ ballots. You wanted a pet theory.”

He adds, “Jeff Mapes suggests either the lack of a hot-button ballot measure or indecision in the Senate race might have suppressed enthusiasm. Could be. My pet theories are these: 1) although there is great interest in the election this year, Oregonians are not getting the kind of attention we got in ’00 and ’04, and are therefore haven’t stirred ourselves to vote, and/or 2) the polls so strongly suggest an Obama win that voters are complacent about getting their ballots in.”

At fivethirtyeight.com, Nate Silver draws some linkage between counties that vote more Republican and lower ballot turn-ins, and converse. But as Alworth suggests, the linkage seems a little thin.

Could it be that the estimate of how many eligible voters there are, is simply higher this year? That some of those many newly-registered voters aren’t showing?

Consider the history, which seems a little over the map. Here are day runups from the general election results over the last decade.

The variation this year? They’ve been variable for a while.