Hi all,
I have a data-set of organizations and their service sites for 2014-2018. Organizations 1) opened new sites; and/or 2) closed some of their existing sites; 3) no change during 2014-2018. For instance, an organization (ID 2) had 3 sites in 2014. One of its sites (ccc) closed in 2016, and it opened a new site (ddd) the same year (2016). In 2017, it had 5 sites after adding two new sites (eee and fff). In 2018, one of its sites (ddd) closed, and it opened a new site (ggg).
I'd like to determine which organizations opened new sites and which ones closed existing ones.
There are over 1000 organizations and the number of sites increased from about 8,000 to 12,000 during 2014-2018.
Thank you for your help.

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input float(num_id year) int site_count str136 SiteName
2 2014 3 "aaa"
2 2014 3 "bbb"
2 2014 3 "ccc"
2 2015 3 "aaa"
2 2015 3 "bbb"
2 2015 3 "ccc"
2 2016 3 "aaa"
2 2016 3 "bbb"
2 2016 3 "ddd"
2 2017 5 "aaa"
2 2017 5 "bbb"
2 2017 5 "ddd"
2 2017 5 "eee"
2 2017 5 "fff"
2 2018 5 "aaa"
2 2018 5 "bbb"
2 2018 5 "eee"
2 2018 5 "fff"
2 2018 5 "ggg"
end