计算在angularjs中单击按钮的次数

I have 5 buttons and I want when I click each of them it will count. For example I clicked the button 1, the counter should increment 1, and when I clicked the button 2 the counter should increment 1 again. So the total of counter to be displayed is 2. Below is the code I've done so far, but it's not working as I expected. What should I have to do ?I have 5 buttons and I want when I click each o