0 %, If you include flaky excuse, 5% in any one year. We were stopped earlier this year simply because we got off the road to make a phone call, got lost, missed a turn, had to circle back, back up. Highway patrol stopped us to check if we were OK. Told him we were just trying to order supper to go from a restaurant in the next town.
Pretty slim. There are hundreds of laws, so the officer can almost always come up with something.
The officer is not obligated to tell you the real reason unless he is making an arrest or writing a ticket, so they can be deceptive.
For example, if I know the car is stolen I may act like its a routine stop for a brake light and tell the person I'm just giving them a warning and they will be on their way shortly. This keeps them at ease while I confirm if the vehicle is stolen.
Time in sight of them. 0 to 1 minute 1% chance. 5 minutes in there sight 10% chance. 15 minuted in there sight 75% chance. Speak to one after it stops you 100% chance of being beat or shot.