USA - I’m Sorry - John Denver
UK - Hold Me Close - David Essex
AU - Love Will Keep Us Together - The Captain & Tennille

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When I turned 18:

USA - Dreamlover - Mariah Carey
UK - Boom! Shake The Room - Jazzy Jeff & The Fresh Prince
AU - I'd Do Anything for Love (But I Won't Do That) - Meat Loaf

HUGE style change within 18 years.