1966 is the only one where the average was over 100.
But it's not fair to have the whole period average over a certain number, basically if there are 5 days over 90 all 5 days qualify but if two out of those 5 days the average was 90 and the other three days it was 106, it would still not average over 100 over the 5 day period, despite those three days being absolutely epic heat.
Yet if the 90 degree days were only 89 degrees they wouldn't be counted as part of the period and the average would shoot up despite technically being a cooler stretch.