On the left there is wealth (/assets, "Vermögen"), then the next part is about the percentage of people who own houses ("Anteil Hausbesitzer"), and then comes the meat of the chart, the difference in gross annual income ("Bruttojahreseinkommen").
I am sorry to venture so far off topic, but I do most of my thinking either in German or in English which makes me vulnerable to stupid mistakes when the two overlap, so I would really appreciate it if you could tell me where I went wrong.