I think it depends on what you do to drive traffic to your website. If you are very active in forums like SuN you will probably get a lot of referral traffic. If you primarely work with SEO you will probably get most traffic from search engines.
So I think it`s very individual. My blog is getting 54% of the traffic from referral sites and 27% from search engines. The rest is from visitors who type the address in the browser. I don`t spend much time on SEO but a lot on forums, which you can see on the numbers :-)