Year	Code
1976	A
1977	B
1978	C
1979	D
1980	E
1981	F
1982	G
1983	H
1984	I
1985	J
1986	K
1987	L
1988	M
1989	N
1990	O
1991	P
1992	Q
1993	R
1994	S
1995	T or W
1996	V
1997	Z
1998	Z or W
1999	X
2000	AB
2001	EN
2002	DT
2003	AD
2004	CL
2005	MA
2006	OP
2007	EO
2008	PJ
2009	LT
2010	RS
2011 –	3-Digit

From 2011 onwards, the figures are compiled from a combination that is no longer comprehensible.