This is the year-on-year value. It says so in the first sentence.. Generally, such drops are most commonly reported as year-on-year values.
maltimore
joined 1 year ago
wow! way to dig deep!
I found the exact location for anyone interested: https://maps.app.goo.gl/RtuV3jA3MskYCgvE9
The desire path can be seen on streetview.

This was my hypothesis as well, but I didn't detect any position where a gate might have been. I'm quite sure the two spots you indicated are leaves.
Good point actually, that makes a lot of sense.
Very interesting, thanks for sharing!