JUST-RELEASED NUMBERS from one of the country’s best-known “think tanks” — and a left-leaning one at that — buttress the arguments made by immigration reformers that stricter enforcement of our laws will ultimately cause many who are in this country illegally to “self-deport” themselves back to their country of origin.

Moreover, those new numbers come on the eve of arguments in what surely will be one of the most high-profile cases heard by the U.S. Supreme Court this year, regarding Arizona’s tough new immigration law.

The Pew Hispanic Center has released figures showing that the number of Mexicans living in this country illegally (although it prefers to call them “unauthorized”) has fallen significantly for the first time in decades. Why the drop? A big part of it is because many illegals are returning to Mexico after finding it hard work here while the U.S. economy continues to lame along.

The forceful laws passed by Arizona, Georgia, Alabama, South Carolina, Utah and Indiana have also helped make a difference. Yet in a telling move, the Obama administration is seeking to undo Arizona’s bellwether law and Democrats on Capitol Hill are promising to gut it, even if it is upheld by the Court.

The number of Mexican illegals living here has fallen by nearly 1 million since 2007, to 6.1 million, Pew says. (Many knowledgeable observers think the actual number of illegals in this country may be twice that figure). Better border enforcement and stepped-up deportations have also played a role, Pew said.

The Obama administration brags that it deported nearly 800,000 people in its first two years, which many would say constitutes a good start. That number is greater than the number deported during the George W. Bush administration — but keep in mind that Bush’s immigration-reform formula would have ultimately amounted to an amnesty for most illegals, had it passed. Moreover, there is good reason to believe that should Obama win a second term, he would pull out all the stops to push the DREAM amnesty act for illegals and give most of those now here illegally a short and sweet “path to citizenship.”

THE NUMBER OF ILLEGALS entering the U.S. has ebbed and flowed through the decades, based primarily on the natural fluctuations of our economy. Pew’s numbers are the latest evidence of that.

Those trying to cross the border to work in this country shouldn’t have to risk their lives in order to do so, or play cat-and-mouse with the authorities once they get here, as is now the case. And they shouldn’t have to work for slave wages once they get here like at present, thanks to unscrupulous U.S. businessmen and growers willing to put their own countrymen out of work and then pocket the difference between what they pay illegals and what they would have to pay legal workers.

What’s needed are a secure border and improvements in the way we issue work visas so as to ensure safe access for those entering our country temporarily. And there needs to be tougher enforcement in order to make sure those stays are exactly that — “temporary.”

Advocates for illegals argue that those in the country have a “right” to stay here, and that the only reform options are a mass amnesty or sweeping roundups of millions of illegals.

But there is a third way, and — helped by the lagging economy — we’re starting to see it work. That is, the enactment of state and local-level laws aimed at making life so uncomfortable for illegals that they choose of their own accord to self-deport themselves back home, and at their own expense.