title: y-values of ggplot+geom_bar not showing properly
body: <p>I am venturing babysteps in ggplots and need some help with the following problem!
  I have a <code>dataframe</code> called <code>dftemp</code> which has the following structure</p>
  
  <pre><code>   Year Month Values
  1   1996   Jan      0
  2   1996   Feb      0
  3   1996   Mar      0
  4   1996   Apr      0
  5   1996   May      0
  6   1996   Jun      0
  7   1996   Jul      0
  8   1996   Aug      0
  9   1996   Sep      0
  10  1996   Oct      0
  11  1996   Nov      0
  12  1996   Dec      0
  </code></pre>
  
  <p>This goes on like this until:</p>
  
  <pre><code>181 2011   Jan     -3
  182 2011   Feb      2
  183 2011   Mar      2
  184 2011   Apr      6
  185 2011   May    -13
  186 2011   Jun     -4
  187 2011   Jul      0
  188 2011   Aug      0
  189 2011   Sep      0
  190 2011   Oct     -7
  191 2011   Nov     -7
  192 2011   Dec      0
  </code></pre>
  
  <p>I tried to make a barchart by:</p>
  
  <pre><code>ggplot(dftemp,aes(x=Month,y=Values,fill=Year))+geom_bar(binwidth=10)
  </code></pre>
  
  <p>And got something weird and wrong (sadly my reputation is not high enough so I cannot post the image)..The resulting plot had y-values that were squished together very tightly by the bottom of the y-axis..</p>
  
  <p>I don't understand what I am doing wrong here! I tried putting <code>factor()</code> in front of the aes inputs but to no avail!</p>