It depends. If you´re using high IR and high AA, the GPU usage will go up. If not, it would keep more or less the % of usage you said.
And yes, for more accurate knowledge of that you´ll need GPU-Z.
And yes, for more accurate knowledge of that you´ll need GPU-Z.
Rig 1: Windows 10 Home | AMD A6-1450 @ 600/1000/1400 MHz | AMD Radeon HD Graphics 8250 | 4GB RAM | HP Pavilion TouchSmart 11.
Rig 2: Windows 10 Pro | Intel Core i7-2640M @ 780/2800/3500 MHz | Intel HD 3000 Mobile | 8GB RAM | Dell Latitude 6320.