Calculate how much of that difference is due to having...

[mtgryphon]

I'm working with a calculation for the adoption rate of a specific technology, comparing projected adoption rate to actual. The adoption rate is calculated by dividing the number of people who have adopted by the number of people who are eligible to adopt. Targets have been set for both of these numbers and are used to calculate the projected adoption rate:

Projected:
Adopters: 45,000
Eligible Adopters: 60,000
Adoption Rate: 75%

Actual:
Adopters: 40,000
Eligible Adopters: 50,000
Adoption Rate: 80%

In this example we are 6.7% above our projected adoption rate. I want to be able to calculate how much of that difference is due to having fewer adopters and how much is due to having fewer eligible adopters than projected. For example, "Our adoption rate is 6.7% above projection. X% of that is due to having fewer adopters than projected and Y% is due to having fewer eligible adopters." I was thinking that X% + Y% should equal 100%, but I don't know if that's true. Can someone help me with this calculation?

Thanks!