在ggplot2中修改轴颜色标签时出现问题

I have a basic question which has turned a headache for me. I want to change the color for the axis value in a plot to blue, but it has been impossible. In the code, I´m using, I plot the mean and Confidence intervals (CI) values for a data summary. I some tutorials to change this (I have a basic question which has turned a head