a) sort the records by asset tag to group them. Use a "count of" summary field and a sub summary layout part "when sorted by" asset tag number. If you remove the body part, you can list each asset tag once with a count.
b) set up a self join that matches by asset tag field. Then a calculation field can use count to count related records or you can use the summary field from a) if you refer to it as from the related table occurrence.
c) do the same as b) but instead of a self join, use a table where each asset tag is listed once and link by asset tag.
Tell us more about the structure in FileMaker for the data you displayed.
Is each row a separate record and each column a separate field?
Or is this just a series of lines of text in a Text field?