Look at the graphs, though. The majority of Democrats were pro-free-trade the whole way through. It just strengthened gradually over time. The Republicans, meanwhile, bounced violently down, then up, then down, then up again. If that's about "more awareness" I think it's awareness of what the leaders of each party were doing. When, in 2009, McCain was more pro-free-trade than Obama, Republicans as a whole were very pro-free-trade. When Obama started successfully pushing through big new trade deals, they became anti-free trade. Then when Romney was running as a free-trade advocate, they were free trade again. Then when Trump launched his isolationist run, they became wildly anti-free trade. Then when he started negotiating trade deals, they drifted back towards neutrality.