I would expect significant increases in all categories of social-media posts over the past 10 years simply because of the growth of social media. If you're saying you think data would show an increase in the percentage of social-media posts that express "white guilt" (and define that clearly), I disagree, and I would be interested in seeing that point of disagreement resolved empirically.
And on a personal level, I don't think I've ever seen a FB or Twitter post that expressed what you'd call "white guilt" by any of my friends or anyone I follow. Not sure if I've seen it in the WR. I know I've seen hundreds of white persecution fantasy posts here.