| 1971 | Members (17): Austria, Belgium, Bulgaria, Canada, Czechoslovakia, Denmark, Finland, France, Germany (BRD and DDR), Hungary, Japan, Norway, Poland, Sweden, Switzerland, UK |
| 1971 | Members (17): Austria, Belgium, Bulgaria, Canada, Czechoslovakia, Denmark, Finland, France, Germany (BRD and DDR), Hungary, Japan, Norway, Poland, Sweden, Switzerland, UK |