This is something that everyone who has or has run a blog or a website has question him or herself at least once a day.
To discover how many times your article article been shared on FACEBOOK you need to copy the following link (https://graph.facebook.com) + URL you would like to study.
IE: http://graph.facebook.com/https://taxesinspainonline.wordpress.com/2019/01/24/residency-card/
Then, you will see a summary data of the shares and comments like the one below:
"share": { "comment_count": 21, "share_count": 13
It’s very useful to analyse the reach of the articles, something very important to know that you are working in the right way.
I hope that this help all of you.
Very helpful