1.6 Map Asteroid spawn rate not working properly

NOTE I may be completely wrong on this but it looks wrong to me so:

In file MapSetupDefs.xml

<InternalName>Rare</InternalName>

                              <Stars>0.5</Stars>

                              <PlanetFrequencyExp>1.75</PlanetFrequencyExp>

                              <HabitablePlanets>0.30</HabitablePlanets>

                              <ExtremePlanets>0.05</ExtremePlanets>            

                              <Asteroids>0.05</Asteroids>                            ** spawn probability factor

                              <MinAsteroidGroup>1</MinAsteroidGroup>        ** these 2 lines set group size

                              <MaxAsteroidGroup>3</MaxAsteroidGroup>

I did a test (huge map)  where I set

                              <Asteroids>0.05</Asteroids>                                          

                              <MinAsteroidGroup>1</MinAsteroidGroup>              ** a spawn will  gen only 1 roid

                              <MaxAsteroidGroup>1</MaxAsteroidGroup>

Counted aprox # of asteroids, then set:

                             <Asteroids>0.50</Asteroids>                                  ** upped spawn probability factor by 10

                              <MinAsteroidGroup>1</MinAsteroidGroup>             

                              <MaxAsteroidGroup>1</MaxAsteroidGroup>

Restarted game and the the aprox # of roids did not change at all and I would have thought it should have gone up by ~10 (.05->.5)

If i got this all wrong, sorry to bug you