Year	Z-score
1999-01-01	18.18456078
2000-01-01	16.44337654
2001-01-01	16.55241966
2002-01-01	18.99986458
2003-01-01	21.76676559
2004-01-01	24.46567726
2005-01-01	20.01230431
2006-01-01	20.42960930
2007-01-01	17.43763542
2008-01-01	15.07139683
2009-01-01	18.18979454
2010-01-01	17.50815964
2011-01-01	14.13518715
2012-01-01	13.95593071
2013-01-01	14.84770012