The difference is how much kids where biking, which has a lot to do with the utility of biking in a flat high density country.

Utility -> Use -> Risk -> Deaths -> Change

https://www.walkbiketoschool.org/wp-content/uploads/2017/01/...

""" In 1969, 48 percent of students in grades K through eight (ages 5 through 14) walked or bicycled to school.1

 In 2009, only 13 percent of students in grades K through eight walked or bicycled to school.1

 In 1969, 89 percent of students in grades K through eight who lived within one mile of school usually walked or bicycled to school.2

 In 2009, only 35 percent students in grades K through eight students who lived within a mile of school usually walked or bicycled to school even once a week. """

From an American perspective the temptation is to bring up suburbs etc, but being bike unfriendly is a global thing. It’s really about the physical effort to travel X distance and therefore the reasonableness of biking such distances to see a friend.