The world’s final form electronic document format of choice, PDF celebrates its 20th birthday in 2013. PDF files are everywhere, because PDF is the electronic equivalent of the paper page.

Yes, a fixed-format page is pretty old-school. We’re all using wikis now, or SharePoint, or some other thing. Ok, we’re doing all that – and we’re still working with PDF files. Why?

PDF is just so easy. It works, and you know what you’ve got. That matters.

Courtesy of Google’s nifty Trends utility this page tracks relative interest in selected search-terms over time. I’ve stared at Analytics data for too long to make any strong claims about what this means, but the trends certainly seem suggestive. Here’s Google’s explanation of how Trends works.

First, a big-picture comparison of some interesting terms:

The following single-factor charts are intended to get you thinking. Simply click through to Google Trends to perform your own comparisons.

If you’d like to see another concept added, make a suggestion.

NOTE: I apologize that this data is not exposed to screen-readers. This is Google’s problem, ok!