Year	gross (GPI)
1972	0.828069984912872
1973	0.820280015468597
1974	0.830600023269653
1975	0.836650013923645
1976	0.825219988822937
1977	0.823710024356842
1978	0.839950025081635
1979	0.857029974460602
1980	0.849820017814636
1981	0.836220026016235
1982	0.840640008449554
1983	0.852989971637726
1984	0.858690023422241
1985	0.839709997177124
1986	0.863529980182648
1987	0.879119992256165
1988	0.884190022945404
1989	0.893909990787506
1990	0.897819995880127
1991	0.906170010566711
1992	0.915629982948303
1993	0.921570003032684
1994	0.942749977111816
1995	0.950860023498535
1996	0.956529974937439
1997	0.958750009536743
1998	0.967069983482361
1999	0.972670018672943
2000	0.978649973869324
2001	0.978600025177002
2002	0.979719996452332
2003	0.984380006790161
2004	0.993480026721954
2005	1.00508999824524
2006	1.01225996017456
2007	1.02052998542786
2008	1.02946996688843
2009	1.03673994541168
2010	1.01840996742249
2011	1.0200400352478
2012	1.02093005180359
2013	1.02569997310638
2014	1.02967000007629
2015	1.02404999732971
2016	1.02430999279022
2017	1.01924002170563
2018	1.02109003067017
2019	1.02104997634888
2020	1.02060997486115