[FT] Size of "Countries" in FT

Whilst working on the background for my take on the Romanov Hegemony,
I've been puzzling over how big it should be.  That is, how many systems
would it include.  Following on from this, how big are the other powers?
 I've put a quick brain dump below
 
Major powers - NAC, ESU, NSL, FSE - around 25-35
Secondary powers - PAU, LLAR, IslamFed - around 15-25
Third rate powers - RH, OU, FCT IndCW - around 5-15
Others - ScandivFed, independents (Netherlands, Japan, etc) - upto 5
 
If you take the mid range for the above that means that there are around
(say) 250 inhabited/claimed systems out there.	Does that sound
reasonable for only 120 years of FTL travel?  To me it sounds a bit
much.  Any other opinions out there?
 
BTW, before anybody starts saying that any of the above powers should be
in different categories, I am supremely indifferent.  That is how they
will be ranked in my (albeit GZG derived) universe.
 
Colin
(Autocratic Supreme Being in his own tiny little mind)