WASHINGTON (AP) — As American corporations have generated an ever-smaller share of federal tax revenue, the burden has fallen more heavily on individuals, through the income tax and the levies that pay for Social Security and Medicare. President Joe Biden has proposed to stop companies from stashing profits in countries with low tax rates. To do so, he is calling for a 21% minimum tax on multinationals’ foreign earnings and is urging other countries to follow suit. His plan would also rescind what the administration sees as international loopholes in former President Donald Trump’s 2017 tax legislation.