X

U

X×U

GDP

R&D

R-squared

r2_a

Model8

0.367^***

0.040

0.245^***

0.901

0.890

Model9

0.417^***

0.198^**

0.022

0.196^***

0.930

0.919

Mode10

0.116^*

0.008

0.204^***

0.940

0.927