Combine 2 SQLite result sets to calculate percentage
A fellow redditor provided me with the assistance to answer my question.  The following is the end result that did what I needed:

select t.location, printf("%.3f", sum(st.456Clicks))/printf("%.3f", sum(st.123Clicks)) as percentage
from (
    select email, count(*) as 123Clicks, 0 as 456Clicks
    from table
    where test = "123"
    group by email

    union all

    select email, 0 as 123Clicks, count(*) as 456Clicks
    from table
    where test = "456" and "Clicked?" = "Yes"
    group by email
) st
join table t
on t.email = st.email
where t."Clicked?" = "Yes" and t.test = "123"
group by t.location
order by percentage DESC