That's one figure you will never see. First you have to quantify effort. Then, you need to get companies to reveal how much effort they put into each product or service. This ratio will be a closely guarded secret for companies, since it would let competitors understand the quality of the field.
The amount of effort you have to put in is going to be different than someone else. It would be a much better idea to choose something you are familiar with. Something you can can get excited about.
That is good advice but, I'm interested in knowing, which revenue models are known for generating higher amounts of money, generalising and removing the specificities of the people who might be implementing the model.