'80s. Possibly towards the end, when Phoenician were really starting to make their own mark on the designs produced. The other makers all just carried on with the takes on designs that arose at Mdina.
But these Maltese glassmakers are part of what was a completely new art movement which only arose in the '60s, Studio Glass. It's quite a long story, and I can rabbit about it until the cows come home, but I don't want to get boring and take over your thread, which will be put into the paperweight forum rather than sorted by country or manufacturer.
I'll see if I can find other threads which tell it, if you are interested.
Brief summary, off the top of my head.

;-
It started off when two Americans, Dominic Labino and Harvey Littleton got together and invented a small kiln which could be used to melt small volumes of the hot glass metal so that artists, inexperienced in glasswork, could finally use hot glass as a material to work with.
It also had depended on finding the right recipe of metal, which would suit the small kiln. (Which turned out to be the kind of glass used for making marbles.)
On the 23rd of March, 1963, they gave lectures about this new kiln in Toledo, the students loved the idea and the Studio Glass Movement was born. The artist glassmakers had to invent the ways of working themselves.
One of the students attending those lectures was Sam Herman, who fell madly in love with working glass and brought it over to the RCA in London, giving lectures and demonstrations, Michael Harris was the director of the RCA, and he "got the bug" from Herman.
Harris decided to pack up himself and his family and go to Malta to set Mdina up. Making this new kind of art, Studio Glass.
https://www.glassmessages.com/index.php/topic,50103.msg282951.html#msg282951