I had in a way an opposite reaction. I was surprised that the most recent algorithm listed was discovered as long ago as 1987. I didn't notice any date on the paper so I'm assuming it's recent. Judging by the dates, the period of most rapid discovery ended in the mid-sixties, at which point it slowed down and then slowed down much more in the eighties. The overall pattern of slow-down is not terribly surprising (low hanging fruit and all), but that the list ends in 1987 is surprising.