Selbständig vs. selbstständig
Both "selbständig" and "selbstständig" exist, being used in the same context in German. Still, I am not sure if there is a different connotation from one over the other. Which of both is the appropriate one to use?
A Google Ngram reveals that "selbstständig" was very rarely used over almost a century. Only from 2000 onwards it is increasingly used. It looks as if somebody resurrected it:
Was there any good reason for doing so?
If an orthography reform was the cause of people using an old word, did it influence pronunciation? How are "selbstständig" vs. "selbständig" pronounced?