Timeline for Tandberg speakers

While working on my Huldra 10 and Hi-Fi System 20 I were curious to find the timeline for Tandberg speakers.
Not finding an uniform source I gathered catalogs from 1960 onwards and made this compilation listing Tandberg speakers between 1960 to 1977.

For years I never understood the design decision from Tandberg with regards to the black line over the front grill on later HiFi System 15 17 and 20. From pictures it always looked like a piece of wood stained black. Not until I had a set of HiFi System 20 myself I understood that this black line actually are a metal mesh grill to better let through high frequencies.

This PDF file includes all images below plus the schematics and parts list for most modells.