2015 has been an eventful year for Barack Obama. He made a historic nuclear deal with Iran, two of his Supreme Court appointees voted to legalize same-sex marriage nationwide, he's fought with the left to advance his trade agenda, and he gave a speech on race and gun violence that was hailed as the best of his presidency.

And none of that has caused his approval rating to budge in the slightest, as you can see in this HuffPost Pollster chart:

The full trend of Obama's approval throughout his presidency, which you can see here, has had many more ups and downs. This year's rating of 45 percent approval and 50 percent disapproval is mediocre historically, as you can see over at Gallup (it tops George W. Bush and Harry Truman's seventh-year approval, but is well behind Bill Clinton and Dwight Eisenhower's and slightly behind Ronald Reagan's).

Obama's rating is slightly better than it was last year, when it was similarly steady at about 43 percent approval and 52 percent disapproval. But the broader change some expected would result from improving economic news isn't evident yet.

Political scientist Alan Abramowitz has argued that unless Obama's approval makes it back up to 50 percent, the Democrat who's running to succeed him should be considered a narrow underdog. He predicted that Obama's current approval rating of 45 percent would likely result in the Democratic nominee getting 49 percent of the two-party vote share, and therefore losing.

Now, elections aren't simply a referendum on presidential approval (Abramowitz's own "time for a change" model also incorporates GDP growth). And of course, it's possible that future news events could change Obama's approval rating. But all such news events this year have, so far, failed to do so.