I'll give that a try, it'll take a while though.
In the meantime, I found the number of events of Mb>4.5 in the PDE catalog
from 1963 -2000 and in the seven regions.
From 1963-2000 there were 131,327 events of Mb>=4.5 listed in PDE for the world.
Of these, 19,877 occurred in the seven primary regions listed in the forecast.
The simple background rates indicate that 15.1% of global seismicity at Mb>4.5
occur in these 7 regions. This compares with 64% of global seismicity in the
past 10 days (about 4 times as high a rate compared with global seismicity
as in the entire catalog).
The assumption that the rates were similar to Mb>=5.5 for Mb>4.5 was not too
far off - a difference of about 2%.