Average unique users till Date

[kaushi2020]

I am doing a calculation based on distinct users per day. below is my script to find average 

Num(count({$<Year=, Month=, Day=,
Date={">=$(=date(monthstart(max(Date))))<=$(=date(max(Date)))"}>}
Distinct users)
/
//(max(Date)-min(Date)+1)

Day(max(Date)),'#0').

Currently the Average for 2 days shows  - 7658.

when we see the graph it loos as per the attached. 

Is there any way i can calculate Average. 

Expecting this calculation: (7.58k + 8.62k)/2 = 8.1k