| Date | Acquired | Amount |
|---|---|---|
| Nov 21, 2017 | $ 30,000,000 | |
| Nov 09, 2017 | Undisclosed amount | |
| Oct 24, 2017 | Undisclosed amount | |
| Sep 29, 2017 | Undisclosed amount | |
| Jun 26, 2017 | Undisclosed amount | |
| May 14, 2017 | $ 200,000,000 | |
| May 09, 2017 | Undisclosed amount | |
| Mar 23, 2017 | Undisclosed amount | |
| Feb 19, 2017 | $ 2,000,000 | |
| Dec 01, 2016 | Undisclosed amount | |
| Sep 23, 2016 | Undisclosed amount | |
| Aug 22, 2016 | $ 200,000,000 | |
| Aug 05, 2016 | Undisclosed amount | |
| Feb 03, 2016 | Undisclosed amount | |
| Jan 29, 2016 | Undisclosed amount | |
| Jan 28, 2016 | Undisclosed amount | |
| Jan 07, 2016 | Undisclosed amount | |
| Nov 24, 2015 | $ 18,200,000 | |
| Oct 05, 2015 | Undisclosed amount | |
| Oct 02, 2015 | Undisclosed amount | |
| Sep 15, 2015 | $ 25,000,000 | |
| Jun 26, 2015 | Undisclosed amount | |
| May 28, 2015 | Undisclosed amount | |
| May 18, 2015 | Undisclosed amount | |
| Apr 14, 2015 | Undisclosed amount | |
| Apr 08, 2015 | Undisclosed amount | |
| Apr 07, 2015 | Undisclosed amount | |
| Mar 24, 2015 | Undisclosed amount | |
| Feb 24, 2015 | Undisclosed amount | |
| Jan 21, 2015 | Undisclosed amount | |
| Nov 03, 2014 | Undisclosed amount | |
| Sep 23, 2014 | Undisclosed amount | |
| Jul 28, 2014 | $ 30,000,000 | |
| Jul 25, 2014 | Undisclosed amount | |
| Jun 06, 2014 | Undisclosed amount | |
| May 28, 2014 | $ 3,000,000,000 | |
| May 02, 2014 | Undisclosed amount | |
| Apr 04, 2014 | Undisclosed amount | |
| Feb 21, 2014 | Undisclosed amount | |
| Jan 04, 2014 | Undisclosed amount | |
| Dec 23, 2013 | Undisclosed amount | |
| Dec 02, 2013 | $ 200,000,000 | |
| Dec 01, 2013 | Undisclosed amount | |
| Oct 04, 2013 | Undisclosed amount | |
| Aug 28, 2013 | Undisclosed amount | |
| Aug 22, 2013 | Undisclosed amount | |
| Aug 13, 2013 | Undisclosed amount | |
| Aug 01, 2013 | Undisclosed amount | |
| Jul 19, 2013 | Undisclosed amount | |
| Jul 19, 2013 | $ 1,000,000,000 | |
| Jul 18, 2013 | Undisclosed amount | |
| Jul 01, 2013 | Undisclosed amount | |
| Mar 24, 2013 | Undisclosed amount | |
| Oct 18, 2012 | Undisclosed amount | |
| Jul 27, 2012 | Undisclosed amount | |
| Jul 02, 2012 | Undisclosed amount | |
| May 30, 2012 | Undisclosed amount | |
| Feb 23, 2012 | Undisclosed amount | |
| Dec 13, 2011 | Undisclosed amount | |
| Oct 29, 2011 | Undisclosed amount | |
| Sep 20, 2010 | Undisclosed amount | |
| Jul 01, 2010 | Undisclosed amount | |
| Jul 01, 2010 | Undisclosed amount | |
| Apr 28, 2010 | Undisclosed amount | |
| Apr 27, 2010 | Undisclosed amount | |
| Jan 05, 2010 | Undisclosed amount | |
| Jan 01, 2010 | Undisclosed amount | |
| Dec 05, 2009 | $ 17,000,000 | |
| Jul 01, 2009 | Undisclosed amount | |
| Apr 23, 2008 | Undisclosed amount | |
| Dec 05, 2006 | Undisclosed amount | |
| Oct 16, 2006 | Undisclosed amount | |
| Mar 23, 2005 | Undisclosed amount | |
| Jan 22, 2005 | Undisclosed amount | |
| Jul 01, 2002 | Undisclosed amount | |
| Jun 21, 2002 | Undisclosed amount | |
| Jun 20, 2002 | Undisclosed amount | |
| Feb 07, 2002 | Undisclosed amount | |
| Jul 09, 2001 | Undisclosed amount | |
| Apr 01, 2001 | Undisclosed amount | |
| Mar 13, 2001 | Undisclosed amount | |
| Jan 07, 2000 | Undisclosed amount | |
| Nov 02, 1999 | Undisclosed amount | |
| Jan 08, 1999 | $ 5,000,000 | |
| Dec 20, 1996 | $ 400,000,000 | |
| Apr 01, 1989 | Undisclosed amount | |
| Jul 13, 1988 | Undisclosed amount | |
| Jun 29, 1988 | Undisclosed amount | |
| Jun 08, 1988 | Undisclosed amount | |
| Mar 03, 1988 | Undisclosed amount |