Year Hours
2003 3.7
2004 3.6
2005 3.8
2006 4.1
2007 4.1
2008 4.6
2009 5.0
2010 5.3
2011 5.5
2012 5.4
2013 5.3
2014 5.3
2015 5.5
2016 5.7
2017 5.6
2018 5.9