Here’s a link to a great post from the fine folks at CMI (Michele Linn, to be specific) listing “34 Essential Research Reports for More Effective Content Marketing.”
Not all will be applicable to you and your situation, but the range offers a great way to get a handle on how your efforts stack up and, as importantly, how you might more effectively measure your content marketing performance.
A few of my favorites:
And a few I haven’t read but most definitely will:
Econsultancy’s Content Marketing Survey (paid report)