Year	Number
1970	41.22332
1971	39.10539
1972	40.38314
1973	38.32161
1974	37.21537
1975	37.30693
1976	35.75747
1989	36.40558
1990	41.20965
1993	48.67153
1994	57.91294
1998	32.10315
1999	33.18571
2006	42.32602
2007	42.7703
2008	43.72982
2009	42.83639
2010	44.41709
2011	43.51915
2012	44.67743
2013	45.71171
2015	43.38836
2016	44.58162
2017	47.98298
2018	48.78979