Snake Featherston
Banned
Whilst lend-lease was important to the Soviet Union, it was not what tipped the balance. Hitler was probably doomed the minute he invaded Russia, his fate being certainly sealed by not going for an advantagous peace in the early weeks of the invasion.
Actually it's what kept a fair-sized chunk of Germany from dissolving under nuclear fire. Horrible as it sounds the victory of the mechanized Soviet communist armies meant bureaucratic communist despotism, not Nazi attempts to Manifest Destiny most of Europe beyond the 1938 borders of the Empire.
I vote for "less than 1%" on the assumption that the POD doesn't keep Hitler from declaring war on the US.
It that or something leading to that is the POD, I'd go with 10% or so.
If we also butterfly away lend-lease to the USSR, you might make 50%.
That won't prevent the emergence of nukes. Even though the Soviets achieve a draw, nukes destroying Germany would be an apocalyptic end but still the end.