100 year anniversary symbol

Hi,
Assuming that a couple gets married when they are at their 20's, in order to celebrate their 100 anniversary both have to be over 120.... and that is very very unlikely to happend....  The probability for a person to reach 120 is (rough estimation) 0.00001% (one out of 10 million) so the probability for both to do it is 0.0000000001% ...... not enough people in the world to have 1 couple to have a chance to reach it..... Sad, but those are facts of life....
Best regards,

Anniversaries aren't just for marriage, though. Companies, nations, organizations all can get to 100 and beyond... It would seem to make sense to have a symbol that recognizes a century...