%year slope intercept
1993 -0.1239 51.898
1994 -0.1075 47.182
1995 -0.1369 56.256
1996 -0.1030 44.899
1997 -0.1305 53.636
1998 -0.1306 53.822
1999 -0.0990 43.868
2000 -0.1186 48.589
2001 -0.1011 44.893
2002 -0.0995 42.513
2003 -0.1065 45.656
2004 -0.1090 45.967
2005 -0.1256 52.152
2006 -0.0901 40.843
2007 -0.1342 54.438
2008 -0.1138 48.004