Japan USA exchange rates

Picked up a Japanese 1 Yen 1916 silver cert today. On the back someone wrote equal to 6 2/3 cents in US money. Was this the exchange rate in 1916 or can someone pinpoint the year that it was the exchange rate?

See also https://en.numista.com/forum/topic46087.html

In 1916 1 Yen was $0.50 and in 1937 $0.20. After WW2 this became 360¥/$. For 1 Yen to be worth 6 2/3 cents (15¥/$) this has to be somewhere around the start of WW2.

Nice story! Can you share a picture?

Thanks for the input. Adds a little interesting history to that note.

Blue-M