Year	Percent change
1980	26.471
1981	28.048
1982	59.119
1983	101.769
1984	65.441
1985	57.786
1986	86.455
1987	131.966
1988	113.5
1989	19.918
1990	26.65
1991	22.608
1992	15.517
1993	9.764
1994	6.986
1995	35.062
1996	34.35
1997	20.597
1998	15.916
1999	16.565
2000	9.486
2001	6.367
2002	5.037
2003	4.551
2004	4.694
2005	3.99
2006	3.633
2007	3.969
2008	5.129
2009	5.296
2010	4.155
2011	3.404
2012	4.112
2013	3.805
2014	4.02
2015	2.721
2016	2.822
2017	6.044
2018	4.898
2019	3.807
2020	3.108
2021	3
2022	3
2023	3
2024	3