The average stiff rate on ships is something like 18%.
A pretty large number of people who don't tip. I'm certain this is the reason most of the lines have started or are looking at automatic tipping.
On our New Year's sailing on Golden, I went to hand our waitress a tip over and above the auto tip. She advised me the tips were taken care of. I explained I understood that, but this was extra. She was actually reluctant taking it... but DELIGHTED.