The linguistic rise of helicopter parents (Ngram)

https://books.google.com/ngrams/graph?content=helicopter+parent%2Clocation+monitor&year_start=1960&year_end=2008&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Chelicopter%20parent%3B%2Cc0%3B.t1%3B%2Clocation%20monitor%3B%2Cc0