Got an offer from a competitor, used it to negotiate a 20% raise.
Fairly certain the OP was talking about an annual "cost of living" adjustment, and not job searching for a better offer.
Fairly certain the quoted statistic was talking about total results, not people who stayed at the same job.
Ofcourse. That's what unions do.
It's also why inflation is so damn nefarious because unions ALWAYS negotiate a pay rise to match it. Which as you can imagine gets very ugly fast.