Year	gross (GPI)
1971	0.283609986305237
1972	0.305079996585846
1973	0.303149998188019
1974	0.314999997615814
1981	0.436699986457825
1983	0.42059999704361
1984	0.433099985122681
1999	0.539070010185242
2011	0.676990568637848
2013	0.662658989429474
2014	0.6910799741745
2015	0.703029990196228
2016	0.718529999256134
2017	0.743610024452209
2018	0.768459975719452
2019	0.793129980564117
2020	0.826719999313354
2021	0.859139978885651