What ancestry is largest?

Which Ethnicity is the highest in USA??
Apparently German was reported as the highest in the census but i reckon its British (Eng, Scot and Welsh combined). I know Germany sent the most immigrants to USA (7million) but to look at it this way is too basic IMO. On top of 5 Million Brits that emigrated to USA (1820-2000) some 3 million (out of 4M) were of British ancestry in 1790 and at least 1.5M out 4 M canadian immigrants must have been British.Based on my perusing of immigration records 1800-present and the 1790-mid 1800's (a period where Brit' anscestry was by far the highest and when birthrates where alot higher than they are now) censuses I reckon it goes in this order:
1)British
2)German
3)Irish
4)African


I theorise British ethnicity is undercounted for several reasons.

A) The era when the British ethnicity predominated and when alot of British immigration occurred was over 2 centuries ago. (I think in 1790 about 80% of USA= British ancestry when the pop' was about 4 million- so prob' about 3million Brits). because this was so long ago its no wonder why many americans would be unaware of theis ancestry. They r more likely to remember ancestors from more recent immigration waves such as that experienced by Italians, eastern europeans, hispanics etc...

B) Because USA is an anglocised country the fact that someone has an English surname won't spark much interest. But if someone has a German, Polish, italian, Spanish etc... type surname they are more likely to take an interest/be aware of its meaning and Origins. A name like Schumacher or Kawolski is likely to evoke more attention than say Smith or Johnson.

C) These days People tend to forget/take for granted British ancestry in favour of a more appealing/retro ancestry maybe Like Italian-American, Irish-American or african-American. Especially African-americans. The vast majority of these have white lineage that they deny/forget about and don't account for in Censuses. the likelihood is that the main white genes in African-americans is probably English (admittedly there will be alot of others. Probably alot of early inter-mixing would have been by British colonialists and their descendants in 1600s/1700s/1800s.

D) Alot of Canadian-Americans (i think about 4% of US pop') will only report Canadian ancestry- failing to account for British ancestry ultimately further along down the line. NOTE: British is predominant ancestry in Canada. In contrast French-Canadians seem to state clearly that they r French Canadians.

-there are a few other little reasons why i think Brit's have been undermined in the census.
-these links seem to agree with me that Brits have been underestimated.
English Americans - Wikipedia, the free encyclopedia

White American ethnic group
-in 1980 English was reported as biggest ancestry. It is evident that more and more americans are forgetting their British roots.