Yesterday, I found how long extra inning games last. Today, I'm going to look at how often extra inning games are played. Since the data go back to 1950 when less games were played, I simply divided the total number of extra inning games by the total number of games played that year. I also added in a 5-year moving average trend line.

Click the picture to make it readable.

From 1950-1996, extra inning games accounted for an average of 9.69% of all games per year. Since then, the average per year is 8.34%. It's odd that this all begins in the wild card era, but I don't see any reason for a correlation between the two.