title: How to plot two columns in a stacked barplot
body: <p>I would appreciate your help in the following: I'm trying to build a stacked barplot. The fill is the split of business (new and renewed), the Y axis is volume of new/renewed business and the X would be the month. In my data I have two years of history, so I would like to have two stacked columns per month, one for n-1 year and one for n year. However, I don't know how to do this last step... </p>
  
  <p>To clarify, please find below a picture of the data, the plot I have so far and a drawing of my goal. </p>
  
  <p>And here is the code: </p>
  
  <pre><code>ggplot(BUSINESS, aes(fill=Business, y=GWP_mio, x=Date)) + 
    geom_bar(position="stack", stat="identity") +
    scale_fill_manual(values = c("#009E73","Darkblue")) +
    scale_y_continuous(breaks=seq(0,18000000,1000000), labels = scales::comma_format(scale = 1/1000000, 
    accuracy = .1), limits = c(0,18000000)) + 
    theme_ipsum() +
    ggtitle('GWP development') +
    theme(plot.title = element_text(hjust=0.5, size=14, family="Calibri", face="bold"),
          legend.title = element_text(size=11, family="Calibri", face="bold"),
          axis.title.x = element_text(hjust=1, size=11, family="Calibri", face="bold"),
          axis.text.x = element_text(angle=90, hjust=1, size=11, family="Calibri"),
          axis.title.y = element_text(angle=0, hjust=1, size=10, family="Calibri", face="bold"))
  </code></pre>
  
  <p>Any help would be highly appreciated.</p>
  
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