Kylie

In 2018, 7 is the most common age for an American (U.S.) Kylie who is registered female with the Social Security Administration. It is the 620th most common female first name for living U.S. citizens.

In Australia, Kylie first appeared in the top 100 in the mid 1960s (1965 in NSW at #93, 1966 in South Aus. At #91 and 1967 in Victoria at #89) and by the early and mid 70s, Kylie had already peaked into the top 5 (#1 in 1973 in NSW, #1 in 1972 & '73 in South Aus., #3 in Victoria from 1972-5, #3 in Western Aus. In 1972, '74 and '75).
Even though the popularity decreased a bit, Kylie remained in the top 50 after the mid 1970s and through the 1980s (For 1988 - #22 in NWS, #26 in South Aus. And #27 in Victoria), but with the arrival of Kylie Mole (played by Mary-Anne Fahey) from 'The Comedy Company,' which ran from 1988 to 1990, the popularity rapidly decreased. Kylie's last appearance in the top 100 was in 1989 in NWS (#78) and South Australia (#97) & 1988 in Victoria.

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Source: NSW Registry of Births, Deaths and Marriages (NSW), Department of Justice & Regulation (Victoria), South Australian Government Data Directory, Department of the Attorney General (Western Australia)

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EDIT: With regards to Kylie's ranking in South Australia in 1966, if 'Unnamed' wasn't in the top 100, Kylie would have been in 90th place.

I wonder why there is no popularity for Kylie in the Australian records. It's popular in Austalia and in New Zealand.