I don't understand the chart (probably because I don't want to understand the chart)    ;)

The "experts" say to change anti-freeze every year, or evry two years at the longest.  Your cooling system should contain liquid that has a ph of 9 or higher.   Anything lower is eating your engine, radiator, hoses, gaskets, etc. from the inside out.  Again, the "experts" say that you can significantly extend the life of your car, truck, etc. by changing coolant (anti-freeze) every year.