Earthquakes: The scatterplot below was produced to investigate whether, for the period of observation, the data are consistent with the rate at which earthquakes occur in California remaining...

Earthquakes:

The scatterplot below was produced to investigate whether, for the period of observation, the data are consistent with the rate at which earthquakes occur in California remaining constant.

1) Explain why the graph suggests that the average rate at which earthquakes occurred in California was not constant over the period.

2) How did the average rate change over time?