If suicides had gone from one a year to two a year that would be a 100% increase. Percentage increases, as we've discussed here before, are deceptive without baseline information to put the numbers in context.
A 24% increase means the rate increased from 0.0105% to 0.0130%.
41,457 suicides (in a population of 318.9m) versus 33,485. An increase of 7,972.