title: Set label on group multiplot in gnuplot
body: <p>Im plotting one picture with 4 different graphs using gnuplot. Labels for their x and y axes have the same meaning. If Im plotting it like this: </p>
  
  <pre><code>set multiplot layout 2,2 rowsfirst
  
  set xlabel "x"
  set ylabel "y"
  
  
  set title offset -3,-3
  
  set xrange [20:70]
  set yrange [0:15000]
  set title "Plot 1" 
  plot 'data5.list' u 2:1 w lp pt 7 lt 7 lc rgb 'red' notitle
  set xrange [20:70]
  set yrange [0:15000]
  set title "Plot 2" 
  plot 'data5.list' u 2:1 w lp pt 7 lt 7 lc rgb 'red' notitle
  set xrange [20:70]
  set yrange [0:15000]
  set title "Plot 3" 
  plot 'data5.list' u 2:1 w lp pt 7 lt 7 lc rgb 'red' notitle
  set xrange [20:70]
  set yrange [0:15000]
  set title "Plot 4" 
  plot 'data5.list' u 2:1 w lp pt 7 lt 7 lc rgb 'red' notitle
  
  
  unset multiplot
  </code></pre>
  
  <p>I have all four graphs and their labels, but I want to achieve to have one label for all four of them, as in this <a href="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSow2HFNWt-pOpuOo8a943O0J4iQJ4QCWQHt8sTdunRy21gZ2B-Ww" rel="noreferrer">example</a> .</p>
  
  <p>I tried with unset label for other 3 plots, but I get labels only on first of them, while the other do not have labels at all.</p>