I do not think what your looking for exists. What with each area of the country, even in one state, there can be different costs for labor, materials, taxes, etc.
The best I can direct you to is Means
RSMeans Book Search Result
You can develop your own flat rate for each type of job.
Dangerous in my opinion. How can a flat rate for one outlet work in one building, and be appliacble to all buildings, with different conditions etc.
You will need to learn on your own how to estimate. There are courses that will be helful, but none will have the exact answers for your situation.
The failure rate for electrical contractors used to be second after restaurants.
While an electrician may be an excellent tradesman, they usually are terrible businessmen.
How are your estimating skills? Know how to purchase materials? Have a handle on labor and overhead costs?