| Date | Acquired | Amount |
|---|---|---|
| Nov 07, 2017 | $ 100,000,000 | |
| Jul 01, 2016 | Undisclosed amount | |
| Jun 02, 2016 | Undisclosed amount | |
| Feb 10, 2016 | Undisclosed amount | |
| Sep 14, 2015 | Undisclosed amount | |
| Jun 15, 2015 | Undisclosed amount | |
| Jan 30, 2014 | $ 527,000,000 | |
| Jun 19, 2013 | Undisclosed amount | |
| Nov 10, 2012 | Undisclosed amount | |
| Sep 17, 2012 | Undisclosed amount | |
| May 14, 2012 | $ 3,800,000 | |
| Mar 21, 2012 | $ 200,000,000 | |
| Aug 16, 2011 | Undisclosed amount | |
| Aug 01, 2011 | Undisclosed amount | |
| May 18, 2011 | Undisclosed amount | |
| Apr 27, 2011 | Undisclosed amount | |
| Apr 19, 2011 | Undisclosed amount | |
| Apr 01, 2011 | Undisclosed amount | |
| Mar 18, 2011 | Undisclosed amount | |
| Feb 01, 2011 | Undisclosed amount | |
| Jan 23, 2011 | Undisclosed amount | |
| Jan 05, 2011 | Undisclosed amount | |
| Dec 02, 2010 | Undisclosed amount | |
| Sep 24, 2010 | Undisclosed amount | |
| Aug 17, 2010 | Undisclosed amount | |
| Jun 03, 2010 | Undisclosed amount | |
| Feb 11, 2010 | Undisclosed amount | |
| Jun 05, 2009 | Undisclosed amount |