This parameter says that your throttle clogged inside dy carbon in case if this figure close to 100%.
Cars with milage about 25000 km. have about 22% DBW stuck ratio.
Another brand new car have such figure about 0,2%.

So we can assume that first car has a problem and we have to clean up a throttle. Bot throttle is clean like a new.

My question how this parameters is calculated and on which internal components of the throttle it can affect? Throttle plate, throttle bore etc ?

Throttle position sensor - In spec.
Relative Throttle Position Sensor - In spec.