"

True, this is (perhaps unintentionally) misleading. The axes can be properly rendered by adding an extra argument yaxs=""i""  to the plot command (without changing anything else). See the File-page of the graph for the rest of the code.

[...]
plot(browser.years, browser.ie, type=""l"", ylim=c(0, 70), yaxs=""i"", 
[...]"