Tips for diversifying link profile

Hey guys, I have a site that has managed to get many solid backlinks from Tumblr. A little over 5,000 and some of them on very high PR blogs. They are actually all organic, but I'm afraid my link profile might also appear spammy since so many links are coming from just tumblr blogs. The anchor text and context of the links is well diversified by nature so that's ok. But I probably only have 500 other links from non tumblr blogs.

I'm working on diversifying the link profile, but what percentage of tumblr based links should my profile consist of? I will only continue to get more links from tumblr, there's no way I can avoid tumblr from being a big part of my link profile, but obviously I don't want tumblr representing almost all of my links...