Washington (CNN) The first two years of Donald Trump's presidency haven't exactly been filled with stellar ratings from the public.

Trump's approval rating in Gallup has never -- not one time -- been above 50% since he was sworn into office. His overall job approval number in the Real Clear Politics' average is below 44%. Almost six in 10 people disapproved of how Trump has handled the Russia investigation in a CNN-SSRS poll last month

On and on it goes -- bad numbers following bad numbers, leaving the poll-obsessed Trump to cherry-pick a piece of data here and there that suggests he isn't doing all that badly. "Without the phony Russia Witch Hunt, and with all that we have accomplished in the last almost two years (Tax & Regulation Cuts, Judge's, Military, Vets, etc.) my approval rating would be at 75% rather than the 50% just reported by Rasmussen," Trump tweeted in late 2016 . "It's called Presidential Harassment!"

That's Trump's highest mark on the economy to date and the best he did on the 14 domestic and foreign policy issues that Gallup asked. (Trump's lowest issue rating in the new poll? Just 35% approve of how he has handled the situation in Syria.)

"The President's greatest strength in the views of Americans remains his handling of the economy, although his overall approval rating lags far behind it," writes Gallup's Megan Brenan. "Americans' ratings of his handling of the economy and unemployment outpace 12 other issues tested in the latest Gallup poll, and at 56%, his rating on the economy is the highest of his presidency, up four percentage points from earlier this month."

If history is any guide, the strength of the economy -- and, as importantly, whether Americans perceive the economy as strong or weak -- is a major indicator of an incumbent's chances of winning re-election. As CNN's Harry Enten noted last December

"It turns out there has been a clear correlation between said job growth and the ultimate election result. If the economy has the same job growth over the final two years of Trump's first term as it has over the first two years (about 3%), history suggests Trump would be favored to win by a few points."

Things change. An economy seen as booming one month could be seen as lagging in a few months' time.