Hi Ed,
Wish I could give some concrete info, but I didn't find anything either. Found some recent 1914 CJ Ruckers that sold, but not 1915. The last sold graded examples I'm seeing prices for cards around your card's grade on the PSA site was back in 2019. Maybe someone with VCP can give you some insight.
There is one currently on sale on Ebay below. I don't know how useful it is, but it's a PSA 2, so maybe it's a start
https://www.ebay.com/itm/403316135966
Good luck!
Mike