Siw Malmkvist

Siw "Siwan" Gunnel Margareta Malmkvist (born 31 December 1936) is a Swedish singer who has been popular in Scandinavia and West Germany. She had a number one hit in West Germany in 1964 with Liebeskummer lohnt sich nicht (English: Lovesickness is Not Worthwhile), and on 18 July 1964 she became the first Swede to have a hit on the US Billboard chart, when "Sole Sole Sole", a duet with Italian singer Umberto Marcato, enters the chart.

source: Wikipedia