Count number of days in column without an end date?????????

I need a formula that counts the number of days in an entire column where I only know the start date and not the end date (A2:A for example). I have script that inserts a date stamp when an event occurs and this date stamp goes into column A with the most recent on top. The end date is never known, however I need to count the number of days that are currently in the column without knowing the end date. How can I accomplish this?

For example:

	A	B
1	DATE STAMP	NUMBER OF DAYS
2	8/19/2016	7
3	8/18/2016
4	8/17/2016
5	8/16/2016
6	8/15/2016
7	8/14/2016
8	8/13/2016
9	8/13/2016
10	cell is blank
11	cell is blank
12	cell is blank
13	cell is blank
14	cell is blank
15	cell is blank