Year Number of sites (cumulative) Total area (ha)
1929 2 135709
1958 3 160197
1961 5 200127
1990 12 200313.7
2000 14 429857
2001 14 429857
2002 14 429857
2003 17 565956
2004 18 592366
2005 19 603820
2006 18 698701
2007 19 699496
2008 20 735755
2009 43 876031
2010 43 880774
2011 43 880774
2012 44 892546
2013 44 892546
2014 44 892546
2015 44 892546
2016 44 892546
2017 44 892546
2018 44 892860