The grading system used to rate my skills are based on a logarithmic scale, thus making each step a noticable threshold compared to the previous level.

Here's a quick explanation of what each level implies:

1 2 3 4 5 At least one task requiring this skill completed
1 2 3 4 5 Multiple tasks completed, still occationally require guidance with basic aspects of the skill
1 2 3 4 5 This skill is a tool I'm very comfortable with. Only activly seek guidance when dealing with more advanced aspects of the skill.
1 2 3 4 5 Multiple commercial projects requiring this skill completed. Currently is, or has been, employed as a senior developer with this skill as a requirement for the job.
1 2 3 4 5 Other senior developers consider me a guru in this area.