Mean
Difference
Adjusted
P Value
1997 vs 2004 0.5416 0.8480
1997 vs 2009 -0.5576 0.7652
1997 vs 2014 -3.237**** <0.0001
2004 vs 2009 -1.099 0.3075
2004 vs 2014 -3.778**** <0.0001
2009 vs 2014 -2.679**** <0.0001