This year my total was ¥123,559. Last year my total was ¥119,751 so I did a little better but I didn't start detecting here until March last year. I had a lot more time to go though.
Excellent total for the year - i admit i'm a bit jealous that you have 100- and 500-yen coins which hold quite a bit more value than US quarters... the highest-denomination clad coin i'm likely to find!
How common is it to find 100- and 500-yen coins?
Edit: just found your explanation of this very question on the Beach Hunting forum... congrats on a great year!