This paper caught my attention: "Variation of the solar magnetic flux
spectrum during solar cycle 23"
http://onlinelibrary.wiley.com/doi/1...19291/abstract

The abstract concludes: "The extended minimum of cycle 23 shows similarities
with solar cycle 11, which preceded the mini-maxima in later solar cycles.
This similarity is suggestive that the solar cycles following cycle 23 are
likely to have low activity."

Cycle 23 was the last cycle and the current cycle, 24, is showing low
activity. Mind you, the paper is still in press so their prediction has been
rather over taken by events!

Cycle 11 is the one that peaked in 1870, ~ 140 years ago which would fit
with a 70 year cycle of cycles, including the phase which ended ~280 years
ago in 1715 at the end of the 70 year long Maunder Minimum.

Cheers, Alastair.