Year annual % 1978 3.646318732525629 1979 49.24131729796561 1980 25.85479740924838 1981 18.347196457423255 1982 14.562370430297822 1983 19.7334157214106 1984 32.64892362135063 1985 35.47033486174795 1986 30.230363699768198 1987 25.341020067416437 1988 20.668811420815842 1989 18.65216983784797 1990 28.866594693279264 1991 26.679108289799004 1992 30.799670948281886 1993 46.66979072893416 1994 31.500134526131703 1995 29.461022201477828 1996 25.273156798669817 1997 20.72731167365133 1998 14.904350065599692 1999 14.666477706398753 2000 12.324781980742893 2001 15.042413505772975 2002 13.140436282577678 2003 19.239766656868127 2004 14.8869201406815 2005 16.741652395309035 2006 22.116118852373432 2007 16.735534583551793 2008 17.778107551017033 2009 28.42327787261541 2010 18.94831461332471 2011 17.322969786285356 2012 14.391652016690196 2013 13.58890221463145 2014 11.011936136133569 2015 13.343101694296003 2016 11.333118951433084 2017 8.109777961839736 2018 6.991061693513583 2019 8.882279059689598 2020 10.013562314124755 2021 9.075745733567699 2022 11.66330022405662 2023 9.84883453512065