Kendall tau rank correlations for all pairs of data series
pair	tau	p-value
tau( iotot , iptot )	0.720542554902601	4.44089209850063e-16
tau( iotot , gp )	0.465103155046934	1.52809634279549e-07
tau( iotot , invi )	0.449095309969757	4.09501778042554e-07
tau( iptot , gp )	0.267947993216506	0.00250066600064769
tau( iptot , invi )	0.389816264845864	1.10854794221904e-05
tau( gp , invi )	0.316266026195701	0.000362991156398484