Are historic Steam playtime stats available?

I know that Steam tracks certain stats related to the amount of time I’ve played games in my library. The stats that I’m aware of are:

• Time of my current session
• Time spent playing a game over the last two weeks
• Time spent playing a game overall (ignoring time before Steam started counting)

What I would like is to be able to access more detailed information. I want to graph things like how often I am playing a game at certain times of day, or on each day of the week. I’ve got a lot of similar ideas, but all of them basically require knowing exactly when I started and stopped each session – potentially over a very long time.

Does Steam already store this data, or only the information in the list above? If it is, can I query it through an API? I’d assume it would have to be stored on their servers since it’s able to be viewed through browsers and the mobile app.

If it isn’t queryable through an API, is it possible to track it locally? Is the “current session” counter stored somewhere locally and in a readable format? Could I write a script to scrape it every minute and log the data out? This would allow me to gather the data starting now, at least – it’s not the perfect solution but it’s something.