[slazaro]

Just a warning: The X-axis in the graph is not regularly spaced: some labels on the bars are separated by 3 years, some by up to 13.

[markild]

It looks like a logarithmic axis.

A nice way to think of it is that a linear line on a logarithmic axis would look exponential on a linear axis.

[ethanbond]

But it's not a logarithmic axis, so...