Original: Under these conditions, only about one out of every 650,000 C60 cages was doped with a helium atom; with higher pressures (3000 bar), it is possible to achieve a yield of up to 0.1%.
Simplified: Only about one out of every 650,000 C60 were found with a helium atom. But with more pressures (about 3000 bar), it is possible to get as much as 0.1%.