Editing Tanner scale (section)

==Historical data==
In 1970, boys reached the last Tanner stage, the postpubertal stage, on average at the age of 14.9 years and girls around the age of 14 depending on social class and the particular study.<ref>{{cite journal |last1=Marshall |first1=W. A. |last2=Tanner |first2=J. M. |title=Variations in the Pattern of Pubertal Changes in Boys |journal=Archives of Disease in Childhood |date=1 February 1970 |volume=45 |issue=239 |pages=13–23 |doi=10.1136/adc.45.239.13 |pmid=5440182 |pmc=2020414 }}</ref> In the nearly fifty years since those studies, the ages at which children are beginning puberty has only declined: ({{asof|2018|lc=y}}) "The age of puberty, especially female puberty, has been decreasing in western cultures for decades now [...] for example, at the turn of the 20th century, the average age for an American girl to get her period was 16 or 17. Today, that number has decreased to 12 or 13 years."<ref>{{cite web | url=https://vitalrecord.tamhsc.edu/decreasing-age-puberty/ | title=The decreasing age of puberty |website= Texas A&M Health Science Center|date=10 January 2018 }}</ref>