With Libertarian candidate Chad Grimm on the ballot for Governor's race I thought I'd pull up some data on historical 3rd party support. Here's a table showing the 3rd party support for each statewide race since 2002.
I knew there was strong 3rd party support in the 2006 and 2010 Governors races but until I looked this up I didn't realize that a non-trivial level of support for 3rd party candidates is pretty common. There are a lot of races here between 3% - 5%.
The other thing I have noticed is that Grimm's polling has been really consistent (see the tracker below). For the polls in the last month (at the time of this writing) his support scores are 5.88%, 5.00%, 5.00%, 6.00%, 6.00%, 5.00% and 7.27%, it doesn't get much more consistent than that.
I'm still not entirely sure where Grimm's election day support will fall, it's entirely possible that a number of poll respondents who are pledging support for him could either not show up or undervote the Governor's race. They could still also be won over by one of the two major party candidates. But for now I feel a bit more confident about a narrower range than I was expecting before I looked this up.