Year	total route-km
1980	19248
1981	19258
1982	19320
1983	19380
1984	19387
1985	19845
1986	19950
1987	19980
1988	20036
1989	20090
1990	20090
1991	20126
1992	20752
1993	19869
1994	19869
1995	20124
1996	20045
1997	20132
1998	20132
1999	20248.5
2000	19511
2001	19509
2002	19508
2003	19508
2004	19508
2005	19328
2006	18669
2007	18669
2008	19264
2009	18898
2010	18903
2011	18903
2012	18903
2013	18903
2014	18903
2015	18879
2016	18879