Unfortunately, there are no long-running surveys tracking people’s feelings toward the three systems. Because of this shortcoming, we used artificial intelligence to analyze references to the three systems in more than 400,000 newspaper articles published over a span of decades.
We identified every news story that discussed capitalism, communism or socialism using ProQuest’s TDM Studio. ProQuest has digitized almost all the articles in major English-language newspapers – including The Wall Street Journal and The New York Times – starting in the mid-1970s, with partial archives from earlier years.
So this is measuring the attitudes of media instead of people's attitudes. I guess it's useful.