40% of users never touched the forward button even once.
Another way to interpret that data would be "60% of users at least sometimes use the forward button."
The back-forward pair of arrows conveys a very intuitive idea for most people. In the absence of a "forward" button, I wonder how many FF10 users will accidentally click "refresh" thinking that it's the "forward" button. After all, the arrow in the "refresh" button points in the opposite direction of the arrow in the "back" button, and now the two buttons are side by side. It's not difficult to imagine them as a pair. Yeah, one arrow is straight and the other one is curly, but I often think of "forward" as "undo back", and many programs represent undo/redo with curly arrows.
The refresh button has moved since that diagram. It, along with the stop button, now lives on the right edge of the location bar, far away from the back button.
Another way to interpret that data would be "60% of users at least sometimes use the forward button."
The back-forward pair of arrows conveys a very intuitive idea for most people. In the absence of a "forward" button, I wonder how many FF10 users will accidentally click "refresh" thinking that it's the "forward" button. After all, the arrow in the "refresh" button points in the opposite direction of the arrow in the "back" button, and now the two buttons are side by side. It's not difficult to imagine them as a pair. Yeah, one arrow is straight and the other one is curly, but I often think of "forward" as "undo back", and many programs represent undo/redo with curly arrows.