That's not how that statistic is measured. You take the measurement before the change, not after. If you have 2 pages and you're adding one, then 1 is 50% of 2, therefore, we're getting 50% of the space we currently have available added to it. Another way of looking at it is this... if you have 1 page and increase it to 2, then you're increasing the space by 100%, not 50%.