Year	gross (GPI)
1970	0.671800017356873
1971	0.693899989128113
1972	0.712670028209686
1973	0.734579980373383
1974	0.78328001499176
1975	0.812479972839355
1980	0.876540005207062
1981	0.889050006866455
1982	0.89385998249054
1983	0.89342999458313
1984	0.904709994792938
1985	0.899940013885498
1986	0.907159984111786
1987	0.909250020980835
1988	0.91855001449585
1999	0.962199985980988
2000	0.970409989356995
2001	0.962180018424988
2002	0.944649994373322
2003	0.964600026607513
2004	0.93383002281189
2005	0.95169997215271
2006	0.954370021820068
2007	0.946319997310638
2008	0.954289972782135
2009	0.950529992580414