Year	Number
1977	3.2362221909864464
1978	2.1745639520671567
1979	4.1948929335942715
1980	4.513740225826387
1981	1.9831063715900012
1982	1.9248881246930238
1983	2.1479038655754596
1984	2.181322871616378
1985	3.190043445115883
1986	4.311474718862117
1987	5.241911010329736
1988	5.244884201595963
1989	6.5629325884836955
1990	6.327169698430583
1991	6.775869038049758
1992	7.48475000093322
1993	8.926169124593946
1994	8.855090097824684
1995	8.134650728773188
1996	10.175224451420721
1997	10.863491697185594
1998	12.325074515381328
1999	8.209328766586573
2000	8.671263787390464
2001	8.588007141589301
2002	7.008370765450635
2003	5.649636312938024
2004	6.204273665412292
2005	6.617201164644403
2006	8.2753000187409
2007	7.3705376179558
2008	5.901557657113195
2009	6.4255387635574825
2010	4.955279188912129
2011	4.572590038179635
2012	5.017032650006542
2013	4.899550467408179
2014	4.479488448816296
2015	4.794502844983274
2016	5.871848956396204
2017	5.882137436911894
2018	5.038026812798297
2019	4.86772977033746
2020	6.151620465775144
2021	5.631087878217846
2022	4.544712869889215
2023	5.216112066841466