They are indeed rare, but I think there were a few in the US .. my friend ( and neighbor ) had one .
Then of course there’s Horizon blue ( I love that one ), Cobalt blue ( love that one also ), Maritime blue ( overpowering for my taste ) Tahoe blue ( also nice ). Iris blue ( which I have, so needless to say.. ) and two separate shades of Midnight blue ( very stately ) almost indistinguishable from one another. Have I missed a blue

?
Anyway Jeff Coe, the master keeper of the 968 register can tell you where they all are .. I don’t know how to get a hold of him, but other members on this forum will know and hopefully chime in here ..