Google flights has a good historical estimator. Pick any city pair (even multiple city pair) and dates, business class, select a flight, tells you typically goes for 1350-7400 and $3300 is typical (where did 1350 come from, I'd like to buy that)

Of course covid uncertainty and other factors can mess up this pricing


June might be too early to check (airlines usually open up booking 300-360 days ahead)