Given the simple plot below, is there a way to adjust the y axis such that the range 0-6 takes 75% of the axis, while the rest (7-15) is shrunk into the last 25% of the y axis? I've looked at gap.barplot, but it doesn't let you specify the proportion of the axis for each section.
counts <- table(mtcars$gear)
barplot(counts, main="Car Distribution",
xlab="Number of Gears")