title: Lubridate week() to find consecutive week number for multi-year periods
body: <p>Within R, say I have a vector of some Lubridate dates:</p>
  
  <pre><code>&gt; Date
  "2012-01-01 UTC"
  "2013-01-01 UTC"
  </code></pre>
  
  <p>Next, suppose I want to see what week number these days fall in:</p>
  
  <pre><code>&gt; week(Date)
  1
  1
  </code></pre>
  
  <p>Lubridate is fantastic!   </p>
  
  <p>But wait...I'm dealing a time series with 10,000 rows of data...and the data spans 3 years.</p>
  
  <p>I've been struggling with finding some way to make this happen:</p>
  
  <pre><code>&gt; result of awesome R code here
  1
  54
  </code></pre>
  
  <p>The question:  is there a succinct way to coax out a list of week numbers over multiyear periods within Lubridate?  More directly, I would like the first week of the second year to be represented as the 54th week.  And the first week in the third year to be represented as the 107th week, ad nauseum.</p>
  
  <p>So far, I've attempted a number of hackney schemes but cannot seem to create something not fastened together with scotch tape.  Any advice would be greatly appreciated.  Thanks in advance.</p>