[dehrmann]

It was in 1995. We briefly flirted with 18%, but it's 20% now. At least for restaurants, taxis, and barbers. I've been prompted for tips at self checkout kiosks and tip a generous 0%.

[marky1991]

Why should the percentage change over time?

Given that it's a percentage it already accounts for inflation, so I see no reason to ever change the default.