1995=50,4; 1996=51,4; [1997]=52,4; 1998=53,4; 1999=54,4; 2000=55,11; 2001=56,11; 2002=57,11; 2003=58,11; 2004=59,8; 2005=60,8; 2006=61,8; 2007=62,8; 2008=63,8; 2009=64,8; 2010=65,8; 2011=66,8; 2012=67,8; 2013=68,8; 2014=69,8; 2015=70,8 von: American psychologist (ISSN: 0003-066X)