Let me make sure if I have understood the requirement fully. You have 3 chart objects with following information.
Chart 1 : Categories per Year
Chart 2 : Countries per Year
Chart 3 : Countries & Categories per Year
Now, when the user selects only Category then you wanted to show Chart 1 and hide other two charts. Vice-versa when the user selects the Country. And only when user selects both Country & Category you wanted to show the both the charts. Is this right?
If this is what you need then I am attaching an example. You need to use the below expression under Layout Tab > Show > Conditional