Glen;

Perihelion starts in early January, apehelion in early July.
I sorted all the mag 7+ quakes from 1900-2007 into monthly
bins and also counted north and south separately.

 Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec
  73   60   73   64   74   74   69   73   55   76   94   81 Date 
  48   38   56   47   39   44   42   48   33   45   62   49 North lat.
  25   22   17   17   35   30   27   25   22   31   32   32 South lat.

Roger