Disaggregating (interpolating) annual data to quarterly data with R
<p>My data takes the following form:</p>

<pre><code>df &lt;- data.frame(year=c(1992:2015), share=c(31.9,   36.8,   38.2,   39.9,   36.3,   36.5,   35.6,   35.2,   34.8,   33.2,   33.5,   34.6,   
                                            36.3,   36.2, 38.1, 37.2,   35.9,   33.2,   36.9,   36.0,   33.9,   33.7,   34.3,   35.1))
</code></pre>

<p>The data consists of <strong>average</strong> annual values. I want to convert the data into <strong>average</strong> quarterly values, assuming that the change is linear.</p>

<p>I tried using the <code>library("tempdisagg")</code> , but I can't get it to work. I've also tried some other approaches with <code>library("splines")</code> in stats, but to no avail. Perhaps because I'm handling the date and time-series format incorrectly.  </p>

<p>To clarify, the expected output would look something like this:</p>

<pre><code>y_q     share
1992q1  values
1992q2  values
1992q3  values
1992q4  values
1993q1  values
1993q2  values
1993q3  values
1993q4  values
1994q1  values
1994q2  values
1994q3  values
1994q4  values
</code></pre>

<p>Any help would be much appreciated.</p>