Mixed Data column

Yeah - the trick is to use HASONEVALUE(Table[Total Visits]) or HASONEFILTER(Table[Total Visits]) or ISINSCOPE() in order to identify the totals column - you can see this page for more details: https://www.sqlbi.com/articles/distinguishing-hasonevalue-from-isinscope/

Next is to update your DAX, which you can do in a pattern like:

Measure = IF(HASONEVALUE(Table[Visits]), 
    // your code for calculating the percentage here,
    // your code for the total here
)

Ideally, you would keep that as a number, and then use the dynamic format strings to show those number(s) as a percentage in the values, and then a number in your totals. You can use something like:

IF(HASONEVALUE(Table[Visits]), "#0.00%", "#########")

Read more about format strings here: https://www.sqlbi.com/articles/introducing-dynamic-format-strings-for-dax-measures/.

Hope this helps.