The main importers are the United State with sales of 61 milliards, followed by Japan with a 52 milliards worth importation (amount? ) (P11) (don't worry about P11, it's a reminder for me!)
Thank you!
I've lived my whole life without ever encountering the word 'milliard' before!
So, if I have a milliard, does that make me a milliardaire?
Yes, but it needs a little work:

The main importers are the United States with sales of 61 milliard , followed by Japan with 52 milliards' worth of imports.

That's how I would fix it and use it, with minimal change.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Thank you, MrM! (f)
 Clive's reply was promoted to an answer.
Me too, Clive! I had also never heard of the "Saxon genitive." --khoff
Students: We have free audio pronunciation exercises.
Me neither. I think 'the Saxon genitive' sounds like what the Normans called the peasants' naughty parts.