title: How can I modify the y-axis of a faceted ggplot to make my geom_line more easily visible?
body: <p>I have a figure depicting incidence over time showing a line tracking incidence, confidence ribbons, and colored bars indicating the introduction of a vaccine. I want to change the y-axis to make the y-values smaller so that the incidence line is more visible, including cutting off the error ribbon if I have to. How would I do that?</p>
  <pre><code>a = ggplot(data=d5y, aes(x=year_firstpcv, y=incidence)) +
    geom_line(size=1, colour=&quot;lightslateblue&quot;) +
    labs(title=paste(&quot;Serotype 2 IPD Incidence rate per 100,000 relative to year of PCV introduction, Age &lt;5 years&quot;)) +
    geom_vline(data=d3, mapping=aes(xintercept=pcv13_intro, size=0.1), alpha=0.2, color=&quot;dark green&quot;) +
    geom_vline(data=d3, mapping=aes(xintercept=pcv7_intro, size=0.1), alpha=0.2, color=&quot;dark blue&quot;) +
    geom_vline(data=d3, mapping=aes(xintercept=pcv10_intro, size=0.1), alpha=0.2, color=&quot;yellowgreen&quot;) +
    geom_ribbon(data=f13, aes(x=year_firstpcv, ymin=ci.lowst2, ymax=ci.highst2), linetype=2, alpha=0.15, 
                fill=&quot;lightskyblue&quot;) +
    scale_x_continuous(limits=c(-10,18), breaks=c(-10, -8, -6, -4, -2, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18)) +
    scale_y_continuous() +
    theme(panel.border = element_blank(), panel.grid.major = element_blank(), panel.background = element_blank(),
          axis.title.x = element_blank(),axis.title.y = element_blank()) +
    facet_wrap(.~site, scales=&quot;free&quot;, ncol=4) +
    theme(legend.position=&quot;none&quot;) +
    labs(x=&quot;Year relative to PCV introduction&quot;, y=&quot;Incidence per 100,000&quot;)
  
  a
  </code></pre>
  <p>Produces this plot:</p>
  <p><img src="https://i.stack.imgur.com/LzWD7.png" alt="Incidence facet plot" /></p>