title: x-axis labels are not showing at some plots (stacked bar plot)
body: <p>I am designing a sheet with multiple plots, but for all the bar plots with only one bar the x-axis label isn't shown. 
  How can I make the axis label be shown at all my plots?</p>
  
  <p>Here is my result:</p>
  
  <p><img src="https://i.stack.imgur.com/5IG7Y.png" alt="The result I get"></p>
  
  <p>Here is my code:</p>
  
  <pre><code>library(utils)
  library(RColorBrewer)
  library(readr)
  library(readxl)
  rm(list=ls())
  
  color &lt;- brewer.pal(6,"Spectral")
  overlap &lt;- read_excel("overlap.xlsx")
  par(mar=c(3,3,1,1),mgp=c(2,0.9,0),xaxs="i", yaxs="i")
  
  
  overlap.dat &lt;- overlap[overlap$`Countries and areas`=="Pakistan",]
  overlap.dat &lt;- t(overlap.dat)
  colnames(overlap.dat) = overlap.dat[5,]
  overlap.dat &lt;- as.matrix(overlap.dat[-c(1:8,14),])
  
  barplot(overlap.dat, main = "Pakistan", col = color, ylim = c(0,100), xlim = c(0, 8),
          cex.names = 0.8, names.arg = colnames(overlap.dat), legend = TRUE, 
          args.legend = list(x = "topright", y = 100, cex = 0.8, bty = "n"), las = 2 )
  </code></pre>