Hi there
Libreoffice Calc 5.3.02 → R2= 0.886442
MS excel 2017 → R2 = 0.5669
to calculate R2 in Libreoffice I follow this Trend Lines - LibreOffice Help
(select the chart and insert - trend lines - linear)
data used
1996 | 20.67
1997 | 19.09
1998 | 12.72
1999 | 17.97
2000 | 28.5
2001 | 24.44
2002 | 25.02
2003 | 28.83
2004 | 38.27
2005 | 54.52
2006 | 65.14
2007 | 72.39
2008 | 97.26
2009 | 61.67
2010 | 79.5
2011 | 111.26
2012 | 111.67
2013 | 108.66
2014 | 98.95
2015 | 52.39
2016 | 43.73