根据下面资料，回答题
More than 30,000 drivers and passengers who sit in the front of the vehicles are killed or seri-ously injured each year. At a speed of only 30 miles per hour it is the same as falling from a third-floor building. Wearing a seat belt saves lives:it reduces your chance of death or serious injury by more than a half.
Therefore drivers or front seat passengers over 14 in most vehicles must wear a seat belt. If you do not, you will be fined up to ~ 50. It will not be up to the drivers to make sure you wear your belt. But it will be the driver´s responsibility to make sure that children under 14 do not ride in the front unless they are wearing a seat belt of some kind.
However, when you´re reversing your car, you do not have to wear a seat belt; or when you are making a local delivery or collection using a special vehicle; or if you have a valid medical cer-tificate which excuses you from wearing it. Make sure these circumstances apply to you before you decide not to wear your seat belt. Remember that you may be taken to court for not doing so, and you may be fined if you cannot prove that you have been excused from wearing it.
How many people in the front of the vehicles are killed or seriously injured every year?