Year	% of revenue
1991	16.85439560439555
1992	9.071176337188582
1993	6.626832396493818
1994	10.411586150407752
1995	7.322047965567326
1996	9.062248801869284
1997	8.000893673166685
1998	9.48360081104008
1999	9.796898956398179
2000	7.924249426457429
2001	6.935116451376711
2002	7.86207448234524
2003	7.483835393769418
2004	7.348087325701437
2005	7.940304781294421
2006	9.250868564798404
2007	9.795455759325836
2008	9.206931599699173
2009	9.40899004367262
2010	8.37206826086582
2011	7.999680683695673
2012	6.717764300695361
2013	6.896498720050815
2014	5.944520863520116
2015	6.692024206683432
2016	7.394483685054383
2017	7.291562669159957
2018	6.057018044303901
2019	6.064796260761461
2020	5.864702371495763
2021	5.600562135972434
2022	8.47136772675387