Why do the Member Count and Total Member Count fields for the "List Access By Distribution List" (4289353)

In the MessageStats reports, there are 3 questions below regarding the "List Access By Distribution List" report located at "MessageStats Reports" | "Distribution Lists" | "List Access" | "By Distribution List".

Question 1:
Why do the Member Count and Total Member Count fields for the "List Access By Distribution List" report remain zero?

Question 2:
What does "Member count - Total" and "Total member count - Total" columns mean?

Question 3:
What values from Exchange is displayed in these columns?