Of those 100, many are presumably in private collections. (A quick glance at the auction database on Artsy suggests that 2-3 originals of Great Wave are sold annually, so there must be dozens of them privately held.)
The site lists 59 museum locations, which could be nearly complete if we assume 40% of copies are in private collections.
I don't count private copies because I don't know anything about them.
The main reason for the lower number is lack of data, plus some institutions have multiple copies: Boston have 7(!), NY Met 4, British Museum 3, Tokyo National 3, Chicago Art Institute 3, and many with a couple each.
The site lists 59 museum locations, which could be nearly complete if we assume 40% of copies are in private collections.