Now while I agree that this is valid, I would also extend the hypothesis. Here's the distribution table for the mid cycle periods between Crisis Wars.
58 is the peak year, but also look at the numbers surrounding it. Approximately 25 percent of all crisis wars are in the 56-61 year time frame. Only 27 percent of crisis wars occur under 56 years after the previous one.. 0 1 2 3 4 5 6 7 8 9
------- -- -- -- -- -- -- -- -- -- --
40-49 0 1 0 1 1 1 1 2 2 2
50-59 2 2 3 3 3 3 4 4 5 4
60-69 4 4 3 3 2 2 2 2 2 1
70-79 2 2 2 2 1 1 1 1 1 1
Now it's been mentioned before that the September 11th attacks, under different circumstances, might have triggered a crisis war. I'm somewhat skeptical, but let's say it's true, meaning that 56 years passed. I still remember seeing the fear and anger all around me.
Another is the invasion of Iraq; say we found large stockpiles of chemical weapons when we went into Iraq (we actually did find some, but nowhere near what many believed Saddam had) Even worse, say that they had been used against us, like they were against the Iranians and Kurds. That may not be quite enough to trigger a full-scale regenerancy event, but we would have become more aggressive, more fearful of attacks, and expanded the war into other countries that are known to support terrorism. Eventually, we would have triggered a crisis war.
Yes, year 58 has the highest number, but there are 4 crisis wars that occurred in year 56, 57, 59, 60, and 61. The number drops rapidly after that, so I believe that could be part of the hypothesis as well.