Sorry, I can't find it right now. I think it was a youtube video that I watched. However, there's this: https://edition.cnn.com/2023/01/10/politics/russian-artillery-fire-down-75-percent-ukraine/index.html , to be contrasted with this: https://www.pravda.com.ua/eng/news/2023/05/11/7401786/ . My feeling from following the conflict at liveuamap.com is that shelling has decreased somewhat over time.