How important is proof of freelance work for a TN visa?

[wildpbq]

Hi everyone. I have a couple questions regarding applying for a TN visa.

I have a 3 year diploma for graphic design and also three years work experience in that area. While some of that comes from working at a design firm, most of that comes from freelance work. How important is it to prove to an immigration officer that I have done freelance work?

How would I go about doing that? Do I show up to the interview with my portfolio? Do people with largely freelance work histories tend to get turned down a lot?

Any information or past experiences people have had with this kind of thing would be great!

[Steven]

Can't see why it would be relevant, plenty of doctors and the like go in who have been essentially self-employed up to that point.