9-0 is far more common than 5-4, this is pretty common knowledge for anyone that follows SCOTUS, but here's a source[1].

[1] https://www.washingtonpost.com/news/posteverything/wp/2018/0...

Sorry, I see now that my comment was unclear. I mean of the 5/4 splits, I'd be curious what proportion of cases split 5/4 in the expected manner (Democratic vs Republican appointees) versus other alignments (e.g., Sotomayor, Thomas, Gorsuch, and Ginsburg versus the rest).

What you'd actually expect with political parties that aren't particularly cohesive or consistent over time isn't partisan consistency but that judges would vote consistently with the position of their appointing President on issues politically salient at the time of their appointment and less predictably otherwise.

Which, it turns out, is what they tend to do.