Since he took office almost three years ago, President Trump has, on dozens of occasions, tweeted out poll numbers that show him enjoying majority support nationally or overwhelming, even historic (to hear Trump tell it) support among Republicans.

On no occasion have those polls reflected independently calculated polling averages; on many occasions, they appear to have been fabricated out of whole cloth.

Trump’s really leaned into these fantasyland poll numbers of late, using them, it seems, to try to demonstrate to his base — and any potentially wobbly Republicans on Capitol Hill — that he still enjoys broad support from Republican voters and decent support nationally. With impeachment looming, those are indeed lessons that are valuable for him to convey.

It’s just that … they’re inflated or misleading, across the board, and therefore don’t tell the story he’d like.

Allow us to demonstrate, by picking out the two dozens instances in the past three months when Trump has tweeted about his approval rating.

Sept. 9

There are two concrete giveaways to Trump’s questionable use of polls — particularly his ones touting the support of Republicans. The first is the lack of any source. Generally speaking, if you want to share a poll number with people, you might include a link to prove your point. (Particularly if you have non-monogamous relationship with the truth.) When we looked into this last month, we couldn’t find any source at all for Trump’s claim.

The second giveaway that this is probably made up is that it doesn’t move. Trump had been claiming consistently since July that his approval rating was 94 percent. It doesn’t work like that, though. Numbers go up and down, a function of methodological calculations and subtle changes in views.

So what was his approval? We can look to one poll that has been generated consistently each week over the past three months. Conducted by YouGov for the Economist, it had Trump’s approval at a more-modest-but-still-good 85 percent.

Or, to use the format that will follow below:

Actual polling: 85 percent (Economist-YouGov)

Sept. 14

Five days later, his alleged support among Republicans is unchanged.

Actual polling: 85 percent (Economist-YouGov)

Sept. 16

Trump’s national poll numbers are presented differently. He generally touts them with an image of himself doing presidenty things, with the approval rating in big type — and actual sourcing.

Here, as is almost always the case, he’s using polling from Rasmussen Reports, a pollster that is almost always far friendlier to Trump than averages of polls. That’s because Rasmussen doesn’t look at all Americans but instead at people it identifies as likely voters, a group that is always more generous to Trump than other polls.

What Trump’s doing is cherry-picking, sharing polls that present him in the best light. But despite that, he’s still only at 50 percent approval. If we consider an independent average — in this case, FiveThirtyEight′s — we see that Trump’s actual approval is a bit more modest.

Actual polling: 41.8 percent (FiveThirtyEight average)

Sept. 18

Notice that when Trump uses real polling, even cherry-picked ones, the numbers actually change. He’s still vastly overestimating his support, though.

Actual polling: 41.8 percent (FiveThirtyEight average)

Sept. 20

Actual polling: 42.2 percent (FiveThirtyEight average)

Sept. 23

On Sept. 23, Trump tweeted twice about his approval. Remember what was happening at the time: support for an impeachment inquiry was surging among House Democrats as new details about Trump’s interactions with Ukraine came to light.

Actual polling: 42.4 percent (FiveThirtyEight average)

Actual polling: 87 percent (Economist-YouGov)

Sept. 24

One of the interesting effects of Trump’s cherry-picking is that it obscures even positive shifts, since most observers tend to discount Trump’s claims about his polling. On Sept. 24, the day that the impeachment inquiry began, Trump was actually doing slightly better in independent polling. But of course, he still overhyped it.

Actual polling: 43.1 percent (FiveThirtyEight average)

Oct. 3

And here we have our first — and only, during this period — change in Trump’s reported approval among Republicans. Eager to show that impeachment wasn’t hurting him, he cranked up his approval within his party slightly, a big step given that he can only do so five more times.

Actual polling: 86 percent (Economist-YouGov)

Oct. 6

He’s sticking with the new number.

Actual polling: 88 percent (Economist-YouGov)

Oct. 16

Actual polling: 86 percent (Economist-YouGov)

Notice here that Trump is touting a number that’s actually lower than the last national number he shared. That’s the other problem with tweeting about poll numbers that are moving around within margins of error: They go down a lot, too.

Actual polling: 41.6 percent (FiveThirtyEight average)

Oct. 17

A retweet of the tweet above, this one gets special mention for including Trump’s assertion that his approval ratings — which, again, he’s in the process of bragging about — are actually underrepresented because the media is suppressing support for his presidency. This claim, while baseless, is nonetheless better than those occasions on which he’s claimed that one should just tack 10 points onto his approval rating because that would make the result somehow more accurate.

Actual polling: 86 percent (Economist-YouGov)

Oct. 22

Actual polling: 89 percent (Economist-YouGov)

Oct. 29

A record — that he set three weeks earlier, according to previous tweets.

Actual polling: 88 percent (Economist-YouGov)

Nov. 3

Actual polling: 85 percent (Economist-YouGov)

Nov. 4

Actual polling: 85 percent (Economist-YouGov)

Nov. 5

Actual polling: 85 percent (Economist-YouGov)

Nov. 7

Sometimes, he also uses the same images.

Actual polling: 41.4 percent (FiveThirtyEight average)

Nov. 9

Actual polling: 86 percent (Economist-YouGov)

Nov. 18

Actual polling: 41.2 percent (FiveThirtyEight average)

Nov. 23

Actual polling: 87 percent (Economist-YouGov)

Nov. 27

Actual polling: 87 percent (Economist-YouGov)

Dec. 5

And finally, we get to his tweets Wednesday.

Actual polling: 41.6 percent (FiveThirtyEight average)

Actual polling: 89 percent (Economist-YouGov)

How far off are Trump’s tweets? On average, he overstates his Republican support by 8.3 points. He overstates his overall support by 9.2 points.

In other words, if Trump shares a poll number, it’s not the case that one should tack on 10 points to better approximate reality. Instead, you should subtract 10 points to get a better sense of where things stand.

Just a tip for any Republican senators who are considering their next steps.