How do I add more date tick marks to X axis?
<p>I have some time series data that I am simply trying to plot in R. I would like the X-axis to have ticks for every month: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec</p>

<p>I am only able to get ticks for every other month.</p>

<p>Below is the code I use as well as the resulting plot:</p>

<pre><code>plot(x2,y, col="red", main = "September 2009 Forecast - Bagger", 
     xlab = "Month", ylab="Sales")
</code></pre>

<p><a href="http://i.stack.imgur.com/SdEba.png" rel="nofollow">enter image description here</a></p>