There's nothing like "total domination." China only provides 15.5% of
US imports. Mexico and Japan, together, make up 19%. Canada is 16.4%.
And so on.

Is this based on dollar amounts, or per unit?

Dollars. If you tried to do it in units, you'd have to ask, units of
what?

Units of product.

Toy whistles, or diesel engines?

Yes. : )

How many toy whistles manufactured in the US? How many imported from China?
How many from elsewhere?

Obviously you can't compare whistles to diesel engines... Pick a product and
compare that.

Of course the Chinese will have a smaller percentage of the DOLLAR value
of imports... their cheap prices is what brings it in.

Not so cheap that 15.5% of dollar value would represent "total domination"

It is if it's the highest percentange and the next highest percentage is
only 10%...

If 90% of all imports only accounts for 10% of the dollar value of
imports then dollar value isn't a very good measuring stick.

True enough. Now, why don't you check a few representative products and
see how China's prices compare with others? What you'll find is that, in
comparable products, their price advantage is nowhere near enough to jump
from 15.5% to "total domination."

Not really possible. Walk into consumer stores and try and find a USA made
television or microwave oven.

I'd call it domination when 90% of the stock in a store is made in China.