How soon do you know when an NBA game is done?

Looking at play-by-play data of every game of every season between 2004-05 to 2015-16, I was able to determine at every second whether the team that is currently winning will win the game. I averaged every second of every game (regular and post-season) to come up with the following visualization:

I then averaged each minute to come up with this visualization:

The data can be download here.