don't connect across missing years [lcarr project]

[lindsayplatt]

lcarr branch: missingdata

Lines connect across missing years right now, I want to figure out how to prevent that. BUT I still want a hover to highlight all data for that team.

Example: Derby County is missing data from 2001 to 2005 seasons, but the line doesn't look like that.

[lindsayplatt]

Helpful blog: https://bocoup.com/blog/showing-missing-data-in-line-charts