Improve display of long-term graph

[rixx]

My nom history goes back nearly five years at this point (whee! and thank you as always for this tool). Sometimes I want to see my overall history, which takes a while to render (absolutely fine) and looks generally really well except that the time scale isn't readable at all:

My current solution is to manually append this stylesheet, hiding every marker except every 3rd or 4th:

g[text-anchor=middle] {
  display: none;
}
g:nth-of-type(4n) g[text-anchor=middle] {
  display: block;
}

It would probably be the easiest to either drop the labels during rendering, or to hide them immediately (color=white would do it).

For reference, on my display, Every 3rd entry worked fine for up to ~40-44 months, but 4 years were already better with every 4th entry.