For many employers, the number of years' experience is flexible as long as you have the results to show for the years that you do have. An interviewer uses a preset number of years of on the job experience as a marker for a potential candidate's experience level, but this scale doesn't apply to everyone. This is your opportunity to detail how you've exceeded your career goals and objectives, and why you feel you have advanced ahead of your peers. This may demonstrate you as a desirable fit, and suggest you will advance much faster in their company as well.