Reading further, there were actually five different responses possible: "morally acceptable", "morally unacceptable", "not a moral issue", "depends on the situation", and "don’t know". In a lot of these, "not a moral issue" is a large category. They also left out around a third of the responses that were independent. There's a chart on the fourth page that shows all the responses for the US.
I guess you can still use this to show that the parties don't differ that much in views, or at least the people answering the surveys by phone in 2013 who preferred different parties at that time didn't differ by that much.
Reading further, there were actually five different responses possible: "morally acceptable", "morally unacceptable", "not a moral issue", "depends on the situation", and "don’t know". In a lot of these, "not a moral issue" is a large category. They also left out around a third of the responses that were independent. There's a chart on the fourth page that shows all the responses for the US.
I guess you can still use this to show that the parties don't differ that much in views, or at least the people answering the surveys by phone in 2013 who preferred different parties at that time didn't differ by that much.