The current title is fine. It’s a 50% increase (unambiguously), or a 0.5 percentage point increase (also unambiguously).
But here a 50% increase creates a realistic expectation to me.
"There has been a 1000% increase in traffic deaths this year, we must do something!"
Ah yes, we went from 1 death per year to 11 because there was a fatal bus accident, surely we need to do something.