在ggplot中。如何使轴标题包含符号，如％。

I am making a boxplot in ggplot2. When the plot is made the y axis should read "Straw.P.uptake.%", but instead of % there are two full stops. I have tried adding check.names to remove the full stops from the header names but ggplot doesn't read the names at all when I do that.I am making a boxplot in ggplot2. When the plot