Jing - The best way to do this would be to create a blank survey with one record only which will store total clicked count. You can increment this data value from your original survey using api in survey flow.

KimothiSaurabh Thanks for the suggestion. API in survey flow, do you mean through web service? Can you please share me a bit more guidance?

Jing - Yes, web service in survey flow.
You can create a blank survey with one record only. Let's assume below are details of that blank project that you have created:-
Survey id= SV_XXXXXX
Response id= R_2uHUSIIIII
embedded variable = Total_Visitors
Now in your original survey, we will have following script in survey flow:-
Step 1- to get current visitors count use this web service - https://syd1.qualtrics.com/API/v3/surveys/SV_XXXXX/responses/R_2uHUSl1111
Step 2:- Increase total visitor count and store the current visitor number also.
Step 3:- To update "total visitor count" in that blank survey data, use following webservice.
This way it will first check the total visitor count and increment it by one and then update this new count in that blank survey.
Please don't update total visitors value manually in that blank survey at any point because API can't update the manually edited value.

https://community.qualtrics.com/XMcommunity/discussion/comment/42595#Comment_42595Thanks a lot for the kind illustration Kimothi! I am applying for access to Qualtrics API now. Before practicing, can I check with you, should step 1 and 2 be set on the original survey? should I put them at the very beginning of all blocks? should step 3 be set on the blank survey?

https://community.qualtrics.com/XMcommunity/discussion/comment/42599#Comment_42599Jing - All those three steps would be part of original survey, and yes these would be the first thing in survey flow before any block. Blank survey would be only used for storing visitor count so no action is needed in that survey.