WASHINGTON (Reuters) - The majority of small businesses and non-corporate enterprises known as “pass-throughs” would see a significant tax cut under the Republican tax plan, U.S. Treasury Secretary Steven Mnuchin said on Friday. “Ninety-eight percent of the number of pass-throughs have $500,000 or less of income ... those people will get substantial reductions,” Mnuchin said in a CNBC interview after a key Republican senator earlier this week objected to the current plan over the issue. On Thursday the House of Representatives approved a broad package of tax cuts.  