percentages and multiple query columns

I'm new to Power BI and having a difficulty applying what I'm learning through the hours of tutorials to my particular situation, so your help is greatly appreciated.

Our company rents instruments to school children.  There are a three types of rental accounts:

• those that returned their instrument
• those that ended their agreement by owning their instrument (renting to ownership or paying off their balance early at a discount)
• those that are currently renting

Of the two (three) types of ended rentals, I want to determine what percentage returned their instrument, what percentage rented until ownership, and what percentage took the early pay-off discount.

Here's the infromation I have (both of these pictures represent columns found in the same query):

 Figure A   Figure B

Anyone who is still renting (A 'null' in the Return Date column and a 'P' in the rnt_dunn column) needs to not be taken into account for percentage purposes.

rental return customer - date in return column

owned through rental - null & X with Next Pmt # = Terms

owned through early pay-off - null & X with Next Pmt # does not = Terms

Using these columns/data, how would I get the answer I'm looking for?