Use geom_label or geom_text and provide labels like below.
> ggplot(mpg,aes(cyl))+geom_bar(stat = "count")+geom_label(aes(cyl,85,label=paste(cyl,"cyl",sep = " ")))
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In your case, update paste fucnction with paste([field/variable], "%", sep = " ")
I hope this will do.