Calculating Date Averages - Microsoft Community

i trying write formula averages number of times event occurs on past week, month , year though event not occur every day i.e. no entries in spreadsheet when event not occur. example:

event dates

6/29/17

7/1/17

7/2/17

7/4/17

7/6/17

today's date = 7/6/17

7 days today 6/29/17. event occurred 4 times since 6/29/17 or 7-day average of 5.71 times. there single-cell formula count events occurred on past 7 days (4) , calculate average? , 1 past month , year?

thank able provide.

let's dates in a2:a100

last week: =countif(a2:a100,">"&today()-7)/7

last 30 days: =countif(a2:a100,">"&today()-30)/30

last 365 days: last 30 days: =countif(a2:a100,">"&today()-365)/365

Office / Excel / Windows 10 / Office 2007