show number of books at any given point in time

[codeanticode]

there's no way of telling how many books were read and in what languages at any given point in time, as well as comparatively over time. Can we incorporate this info into the existing scheme, and if so, how, and into which view?
It is important to see the changes in reading patterns, as this is a clear indication of changes in the demographics of the communities, and usually indicates political events or changes in government policies.

[codeanticode]

The tooltips cover this functionality, at least partially. When grouping by emotion, the tooltip shows the number of books currently in that emotion, which is updated as the user moves through time.

The language tooltip shows the total number of books in that language, which is constant. But it could be changed to show the number of read books, or the fraction num read / num total.

[romya]

in the language tooltip showing the fraction num read / num total might be the best option. What do you think?

[codeanticode]

This is how it is done now.