title: Combined graph: geom bar and point how to change location of the point over the first barplot
body: <p>I am facing problem with combining line graph over barplot using ggplot. The bar plot is fine, but when I plot the line, it is positioned directly over each year. I would like to position the line point over the first barplot "C" at each position instead. </p>
  
  <p>Thanks for the help!</p>
  
  <pre><code>tb3 &lt;- structure(list(Year=c("2003","2005","2006","2007",
                          "2010","2012","2013",
                          "Before 2003","2003","2005",
                          "2006","2007","2010","2012",
                          "2013","Before 2003"),
                   tchtype=c("C","C","C","C","C","C",
                             "C","C","R","R","R","R",
                             "R","R","R","R"),
                   Freq=c(145,420,115,134,150,17,142,
                          33,5,3,25,23,4,134,2,237),
                   Local=c(140,393,46,29,26,2,15,2,
                           rep(NA,8))),
              row.names=c(NA,-16L),
              .Names=c("Year","tchtype","Freq",
                       "Local"),
              class="data.frame")
  
  ggplot(data=tb3, aes(x=Year, y=Freq)) + 
    geom_bar(aes(fill=tchtype, linetype=tchtype, color=tchtype,width=.8),
             stat="identity", position='dodge') +
    geom_text(aes(label=Freq,group=tchtype),
              position=position_dodge(0.8), vjust = -1, size = 3) +
    scale_color_manual(values = c("black","black")) +
    scale_fill_brewer(type = 'div', palette = 'Greys', direction = -1) +
    theme_bw() +
    geom_line(aes(x=Year, y=Local, group=tchtype)) +
    geom_point(aes(x=Year, y=Local, group=tchtype)) +
    ylab(label="Number of teachers") +
    xlab("Year of appointment") +
    theme(legend.title=element_blank(),
          legend.position=c(.75, .75))
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/EXBPP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EXBPP.png" alt="enter image description here"></a></p>