Oh Jesus Christ... how generalised are we being here? Because he saved the UNIVERSE, but not necessarily Earth... and do we mean with Vegeta/Gohan/Goten/Trunks/Piccolo/Krillin's assistance, or alone?
If we're talking about the planet, totally alone, then it'd be one. If we're talking about with other people's assistance, then it'd be about four, and if we just mean Universe, then it'd be more like six.