On page 830, the graph shows that a daily dose of 75 - 150 mg of aspirin reduces vascular events by 32%. Taking less than 75 mg a day does not significantly reduce the event rate. Taking 160 - 1550 mg a day significantly reduces vascular events--- but the benefit is not superior to 75 - 150 mg a day, and according to the odds reduction rate (on the right hand side of the graph) the optimal daily dose of aspirin is 75 - 150 mg / day resulting in a 32% odds reduction.