Help on Yes/NO per filtered employee

[hawkeyedm2003]

I have spreadsheet that I have formulas populating if value exceeds a certain value it shows as "aged" (B1). This is reported as a yes or no response.
The raw data includes many employees (A1) that when I filter, it obviously changes the amount or Yes's and no's.
I am trying to use a formula to determine a percentage (C1) of no's divided by yes's. It needs to only select the yes's and no based on the employee filtered to.
Hopefully that made sense. I've messed with the COUNTIF/COUNTA but I cant figure out how to only select the criteria when the single employees is filtered.

A1 B1 C1
NAME Aged? Percentage
Bill Yes
Bill No
Bob No
Bob Yes
Bill No
Bob No
Bob No

[TMS]

Look at the SUBTOTAL function

https://support.office.com/en-us/art...0-e478765b9939