Switch case statement refactoring

I have the following code with switch case statement:

public string IrregularCouponLabel
{
    get
    {
        switch ((ctrl.IrregularCouponFirst ? 10 : 0) + (ctrl.IrregularCouponLast ? 1 : 0))
        {
            case 11: return LocalString.Evaluate("label.Both");
            case 10: return LocalString.Evaluate("label.First");
            case 1: return LocalString.Evaluate("label.Last");
            default: return LocalString.Evaluate("label.None");
        }
    }
}

How should I refactor this code to be more clear and readable or how could I otherwise improve this code snippet?

UPDATE
According to valuable answers
I have updated the code in the following way,

public string IrregularCouponLabel
    {
        get
        {
            return LocalString.Evaluate("label." + GetIrregularCouponValue());
        }
    }

    private string GetIrregularCouponValue()
    {
        bool first = ctrl.IrregularCouponFirst;
        bool last = ctrl.IrregularCouponLast;
        bool both = first && last;
        return both  ? "Both" :
               first ? "First" :
               last  ? "Last" :
                        "None";

    }

What do you think about this? Is it readable or not?

You can use an if statement and the conditional operator:

string label;
if (ctrl.IrregularCouponFirst) {
  label = ctrl.IrregularCouponLast ? "label.Both" : "label.First";
} else {
  label = ctrl.IrregularCouponLast ? "label.Last" : "label.None";
}
return LocalString.Evaluate(label);

You can also use only conditional operators. This way of chaining conditional operators checks take a bit of work to grasp the first time, but it's very compact:

return LocalString.Evaluate(
  ctrl.IrregularCouponFirst && ctrl.IrregularCouponLast ? "label.Both" :
  ctrl.IrregularCouponFirst ? "label.First" :
  ctrl.IrregularCouponLast ? "label.Last" :
  "label.None"
);

StackExchange Code Review Q#7991, answer score: 17