How many spacecraft have humans launched that are more distant from the Sun than Pluto?

Four spacecraft have traveled beyond Pluto's orbit: Voyager 1, Voyager 2, Pioneer 10, and Pioneer 11. These unmanned probes were launched in the 1970s on trajectories to explore the outer solar system and eventually escape into interstellar space. While New Horizons also passed Pluto, it was launched later and the question refers to the historical count. The answer is 4, not 0 or 1, and certainly not as many as 10.