24.1.5.1. Multixacts And Wraparound

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/13/routine-vacuuming.html
Description:

In section "24.1.5.1. Multixacts And Wraparound" of
https://www.postgresql.org/docs/current/routine-vacuuming.html we find the
following sentence towards the end of the section:

"...If the amount of used member storage space exceeds the amount 50% of the
addressable storage space."

I am having trouble parsing "...exceeds the amount 50% of the
addressable..." part.

It seems like the sentence is trying to say "...space exceeds 50% of the
addressable storage space" or maybe even "...space exceeds the amount of the
addressable storage space". Which is which?

Many thanks,
Eric Mutta.