Formula to Summarize Multi Select Text by Group rather than Groupings

I have a list of multi text selections that have about 25 items.

When I summarize the fields, a table displays the selections by grouping:

Item 1      = 1
Item 1, 5  = 1
Item 1, 3  = 1

This is not what I am looking for, therefore, I thought I could write a formula that recognized the group rather than the grouping.

Item 1 = 3
Item 3 = 1
Item 5 = 1