almost an Olympic button

I've had this a few years, came in a mixed lot of buttons, can't remember where from. Seems to be made from aluminium and has a 22mm diameter. What confuses me is that although it seems like an Olympic torch and rings, on closer inspection there are only 4 rings not 5. Was there ever a year when only 4 Olympic rings were used, or would this be something totally different? Any help would be wonderful thank you.