Question : Index fragmentation

I When I do A DBCC DBREINDEX ("HumanResources.Employee", PK_Employee_EmployeeID,80); on my index  on my database 2005/2000 which was 66,66% it changes to 50% and if a do it again on the same index it go up to 85%.
Why is this happening or what should I do

Answer : Index fragmentation

how many records are there in this table? aka: how many data pages does the table/indexes occupy?
the smaller the table, the less meaning does the "fragmentation" have.