Transitions aren't always continuous when changing years

[mdmurbach]

Sometimes the transition between years is smooth (points shifting slightly to their new positions), but sometimes they all fly to the origin and then back out to their new positions (which makes them hard to follow).

For example,

• x = 'Cereal yield'
• y = 'Energy Use Per Capita'
• year = '2003' -> '2004'

I'm not sure why this works most of the time, but not always. Maybe just something to do with the enter/exit placement of the circles?