Count values regardless selection

[david777]

Hello,

I have the following table.

VisitID	PersonID	YEAR
1	1	2014
2	1	2015
3	1	2016
4	1	2017
5	1	2018
6	1	2018
7	2	2015
8	2	2016
9	2	2017
10	3	2016
11	3	2017
12	3	2017
13	3	2018
14	4	2014
15	4	2015
16	4	2015
17	4	2016
18	4	2018
19	5	2016
20	5	2016

I want to count how many PersonID who had at least two VisitID during the period 2017-2018.

The answer should be 2 (PersonID 1 and PersonID 3) even if I make the selection 2018 for field YEAR.

Can anyone help me with this?

Best regards