Add percentage signs to horizontal scale in R likert plot

Question

I am using the likert package in R to plot this graph:

The labels on the horizontal axis are incorrect. What is plotted are percentages. How can I add a percentage sign to the positions indicated in the screenshot?

library("likert")
library("scales")
d <- likert(d)
plot(d, col=myColor) +
  ggtitle("Mechanical Turk") +
  theme(text = element_text(size=20)) +
  # scale_x_discrete(labels=percent) +
  # scale_y_discrete(labels=percent) +
  # scale_y_discrete(breaks=c("A","B","C","D","E")) +
  # scale_y_discrete(labels=c("100" = "100%", "50" = "50%","0" = "0%")) +
  ylab("Percentage of all responses")

I've tried adding scale_x_discrete(labels=percent) but that gave an error ("Error in x * scale : non-numeric argument to binary operator"). The comments show the other things I have tried.

Answer 1

There is a coord_flip() on the likert plot (see likert.bar.plot). try the below:

library(likert)
library(ggplot2)

data(pisaitems)
items29 <- pisaitems[,substr(names(pisaitems), 1,5) == 'ST25Q']
names(items29) <- c("Magazines", "Comic books", "Fiction", 
                        "Non-fiction books", "Newspapers")
l29 <- likert(items29)

plot(l29) + scale_y_continuous(labels=c("100%","50%","0%","50%","100%"),limits=c(-105,105))