I found this really interesting graph at sunlightfoundation.com.
I would like to do one of my own, just with a few style tweaks and updated for 2018, or at least 2017. I checked the source's website, but found no raw data there. Perhaps by "source" they meant they were the ones who put the graph together? I would imagine they must have got their numbers from somewhere.
Question: Is there an open resource for lobbying expenditures? I presume I could then narrow the selection down by topic. I am basically only interested in Net Neutrality lobbying data at the moment.