Is it just me or are those the typical US-centric terms! If so, I'd trust those numbers even less than I already do because they moved the timespans between the graphs.
Okay, let me rephrase that: is it just me or is the application of these terms typical US-centric? "Liberals" in Germany are definitely not the opposite of conservatives. Quite the contrary. The liberals are the go-to ally for the conservatives to form governments here.
Like, do you actually know that? You've said so under different comments here and you sound confident in being right, but.. Could you maybe point me to where you get the 'bog Standart' poli science definition from? And how this applies to the terms used in the study?
I'm sceptical towards the use of (only) liberal vs conservative, but would believe your take if it could be more than a convenient opinion.