better mobile option

[cnell-usgs]

The svg animation is ultra slow on mobile and very small. I'm not sure how much better we can do on improving the speed with the current animation approach.

Other ideas:

• serve up an mp4 of the animation on mobile, remove line chart animation and playback controls to simplify. doesn't improve the viewability of the animation though
• use canvas for animation to make faster - less familiar with how to do this, won't be able to interpolate the path between categories
• break up country into regions that can be selected from a menu, or scrolled through, to be able to make bigger.

For now going to implement #1.