There are a few ways that i'd want to access this:
A toggle at the top right of Calendar (on desktop) that enables an emoji, star rating, colour bar or something visual to see at a glance
On the sidebar, an option to view 'stats'. This could show a rating on the Y axis and dates on the X axis, to plot the ratings along time.
As mobile search and timeline are close to identical, the shortcut could be replaced with statistics, to discover information. I feel the search bar at the top of timeline could be a good place for the new home, or some may want the ability to 'scroll up' to reveal the hidden search bar.
Inspiration from felix
https://howisfelix.today/ is a great project that Felix Krause developed to track days. He offers a variety of good examples of data visualisation on this page.