You do not cause yellow flags without the red message appearing, and you do not cause them without having gone below a certain speed for the given car and place on the track.
However, there are known tracks which can throw a single yellow flag on the count at the very start of the race, and this will not display the red message. This, however, is one flag per race and should have very little effect on your total ratios - particularly for someone with as many laps recorded as you.
If you're expecting your ratio to go down massively because you've done a few clean races, you're to be sorely disappointed - it would take another 1,864 consecutive clean laps to drop your ratio to 30%. Better get racing
Sam