How much percent can rubbernecking contribute on preventing freeway accidents?

It is 1/100 of a whole.

generally, percentage is a fraction whose denominator is a hundred,.eg 65 % = 65 / 100 or sixty five hundredths or 0.65 of something

Estimates vary, but the average seems to be in the area of 3 to 4 times the risk of an accident over drivers who are not drinking. The same statistics, BTW, hold for people who talk on the phone...

26%

1%