What happens when you reach your 5% goal? Do you stop learning/growing/adapting?
I would suggest such a goal be tracked using the mistakes you make. I wouldn't measure it by knowledge of a language. If you want to be a really good programmer then I'd consider, most importantly, ones ability to solve problems quickly, efficiently and accurately. However, I wouldn't consider this to be the only component to the goal. This is a multi-faceted situation, as such should be treated with care if one truly wants to reach it.
I'll try and break it down into bulletpoints and explain in more detail if possible.
Basically being completely self sufficient but can also help others get to the same goal, thus making the whole team more efficient. These are the things I believe make a well rounded software engineer who can tackle any situation, on and off the computer.
Edit::
My answer is in relation to my interpretation of the goal. I changed the goal to How do I become a better developer?
I also agree with j these kind of goals tend to lead to a more ego fuelled way of thinking rather than more important things.