Year	% of revenue
1972	3.462732919254658
1973	2.980392156862745
1974	2.4331696672122205
1975	2.308695652173913
1976	1.8766846361185985
1977	1.9097413318657126
1978	1.9643672910004568
1979	1.327659574468085
1980	1.1627906976744187
1981	0.9736249364237448
1982	1.1939133827545845
1983	1.212043066211076
1984	1.3031403546250802
1985	1.5874576104585443
1986	1.5522416057024948
1987	1.4204430813930027
1988	2.2915974759216207
1989	2.973223799539408
1990	2.66617803164333
1991	2.777319344571496
1992	2.885181162997334
1993	3.2298732199296856
1994	0.29225032752191876
1995	0.6752723474108342
1996	0.24698468251946526
1997	0.27386984770271683
1998	0.046193573311170584
1999	0.1403746916716219
2001	2.209765058878025
2002	2.4825727080516238
2003	3.1417096922456493
2004	3.8540414498414313
2008	2.8923191658660383
2009	3.227021848715731
2010	3.27126917572522
2011	2.7940708980809106
2012	2.4798412532324847
2013	2.102014318481963
2014	1.8338046902922425
2015	2.2466837609762376
2016	1.5604753126287902
2017	1.3136419968173703
2018	1.2828659956526816
2019	1.3681466669156799
2020	1.5828938280872094
2021	1.3112297575249576
2022	2.739696667755747