Year % (cumulative) 1971 1.4726699590683 1981 2.90000009536743 2001 9.09796047210693 2005 9.87814998626709 2006 10.5259799957275 2007 11.2174396514893 2008 11.9547300338745 2009 12.1757202148438 2010 12.472149848938 2011 12.5752000808716 2012 13.2975397109985 2013 14.157036781311 2014 14.4294004440308 2015 15.1314601898193 2016 15.6583518981934 2017 16.8161640167236 2018 17.3764801025391 2019 17.6936016082764 2020 17.7516708374023 2021 17.845983505249 2022 18.1641616821289