Data region's pages fill factor

[Andrey Kornev]

Hello,

I'm a bit confused about the meaning of PagesFillFactor MBean attribute. 
According to the documentation (as well as a tooltip in the JMX MBean Browser 
-- here's a snapshot https://snag.gy/57FVw8.jpg), the attribute indicates "the 
percentage of space that is still free and can be filled in". I'm consistently 
getting  0.99... Does it mean that my pages are 99% empty?