Further mode/year toggle options for the stats page

Currently we have the option to view stats by mode, or to view them all. While that offers a lot of flexibility already, it has one draw back - doing any flying causes the kilometre and carbon emission stats to be absolutely overwhelmed by flying. That one issue aside though, I'm sure there'd be a lot of value in being able to selectively choose which mods to have in the stats, like in the map. And by extension, it could also be useful to have the option to do the same for years too.