How to create a page with the year name? (i.e. “2017”

Not entirely sure if this is the right forum, but on a new WordPress site I want to have a series of pages for different annual events. For example:

https://www.example.org – main landing page
https://www.example.org/2017/ – 2017 event page
https://www.example.org/2017/agenda/
https://www.example.org/2017/speakers/
https://www.example.org/2016/
https://www.example.org/2016/agenda/
https://www.example.org/2016/speakers/
https://www.example.org/2015/
https://www.example.org/2015/agenda
…

This should just be a simple example of creating a parent page and child pages. However, I can’t create a page with the slug “2017” (or any year), presumably because WordPress reserves that slug for use for blog posts that include the year. All it will let me do is use a slug “2017-2”. If I try to edit the slug to “2017” it reverts to “2017-2”, no matter what I do.

Now, I’ve changed the Permalink Settings to be “Post name” so that the year isn’t in the post URL, but WP still won’t let me use plain old “2017”.

Unfortunately, in this particular case, using WP Multisite is not an option (or else I would just create a site for each of the years). I tried putting another parent child above the year, as in:

https://www.example.org/event/2017/

but it still wouldn’t let me create a page with just the year name. And ideally, the goal is to have as short URLs as possible.

Anyone have any suggestions for how I might be able to accomplish this? Or is just not possible with WordPress?

Thanks,
Dan (who has been using WordPress for 12+ years, but never tried to do this particular thing before)