A cyclist

Since 1989 I have made one sample of 100 cyclist each year studying how many cyclists  have a helmet on.  The time has been mostly in the morning when people go to work.  This time it was when they were coming home. This time 80 of 100 cyclist had a helmet on.  I have got this kind of percents on last ten or twenty years. 1989 only a few percent of cyclists had a helmet.