Wow, Block 270658 has $37M in transactions. Over an hour between blocks.
It happens. Sometimes the whole network gets unlucky. Sometimes it gets lucky too but most people don't notice that.
The odds of >40 minutes between blocks is roughly ~2%. On average it will happen roughly once a day.
The odds of >60 minutes between blocks is roughly ~0.2%. On average it will happen roughly once a month.
The odds of >90 minutes between blocks is roughly ~0.01%. On average it will happen roughly once a year.
The odds of >120 minutes between blocks is roughly ~0% (tiny number). On average it will happen roughly once every decade.
The odds of >150 minutes between blocks is roughly ~0% (tiny number). On average it will happen roughly once every century.
Note the ranges are rounded to nearest full unit (day, month, etc) to make it easier to understand/relate on relative rarity. I sacrificed a small amount of accuracy to come up with ranges that are easy to understand.
Of course all that also assumes the network isn't under attack and the actual hashrate is roughly equal to the hashrate required for current difficulty.
