From Google image search. That car may have been available in 2016,17 and 18. I can't believe I have never seen one.
From searching Autotrader. It was only the 2016s that got those wheels. Wonder why.
I'd congratulate you on the nice looking car but if your car is white then why did you post a pic of a blue car that I assume isn't yours?
Someone paying for the 18" wheel upgrade probably is a lot rarer than not especially since they have a very sporty look to them. The Tech package would be a more popular upgrade though. Most people buying a Titanium would be in it for the technology and more upscale nature, not making it sporty.
Autotrader isn't a good source for getting definitive answers for factory options. You need to look in a Ford sales brochure for answers:
2016 Ford Focus Brochure (auto-brochures.com) Just change the year in the address bar to view them.
Those particular 5 star wheels were optional on Titanium models if you elected to get the 18" wheel package for $625 in both 2015 and 2016.
You aren't going to find production numbers for individual options or probably even trim levels like S, SE, SEL, Titanium, ST, RS. Ford doesn't care to release that info anymore and this isn't a classic Mustang where that info is out there.
Some options for the 2016 Titanium:
Ruby Red Tinted Clearcoat – $395
18” Wheel Package – $625
Technology Package (Blind-Spot with Cross Traffic Alert, Lane Keeping Assist) – $795
Cold Weather Package – $195
Navigation Voice- Activated – $795
Active Park Assist – $395
Exterior Protection Package – $245
The tangerine, white tri-coat, and blue candy were also options on the 2016 Titanium for an extra cost. If you have white and it's a Titanium then it was an upgraded option as that was the only white available on that trim in that year.