I'm a bit sceptical of the comparability of these countries' ancestry data, the censuses are all different in method, and self-reported ancestry is heavily conditioned by local culture.
The most obvious example of self report issues is the determination horsehockey which Latin American country has the most "Spanish" descent. Self identification with European descent can look very different from country to country there.
And for censuses, Canada for example asks for "ethnic or cultural origin of the person's ancestors" and provides space for up to six responses which allows for indigenous groups, ethnoreligious ones, and national origins.
Australia just asks "what is the person's ancestry" and collects two responses.and has no ethic or race element on any questions. This can make disentangling, say, the national origins of ethnically Chinese people tricky.
The US has "what is your ancestry or ethnic origin" and also collects two responses, but also asks a race question.
Mexico rather specifically doesn't collect much of anything outside Indigenous groups and is probably not comparable like for like with many other countries.
Brazil appears to only collect race on the census, not ancestry, and is probably not super comparable either.
This is all to say nothing of the trickiness of assigning ancestry from these countries to modern European states in some cases. A lot of those Ukrainian, German, Polish, Greek ancestors may well not be from those modern national territories.
As a side note there, just for fun, while there's a lot of Macedonians in Australia, the language is as common as either Serbian or Croatian, and there's plenty of football clubs sporting the yellow sun and red colours, I think a fair chunk of the Macedonian folk are actually Slavic speaking Macedonians who came from the Greek national territory after the war and the civil war. There's plenty of Yugoslavian Macedonians too, but it's both groups.