Whenever you need to create a chart with multiple series, you will go there and hardcode those series, creating an almost identical SQL for each one of them. As long as your values remain the same, that will be ok. But what if they change? Actualy, the solution is pretty simple - you need to create a PL/SQL Block to return all the series in one SQL. This example in my Demo Application shows how to write such a Function.
If you replace the column and table names, you can use the same function for all of your charts with multiple series.