Wii Fit and Wii Fit Plus were developed by Nintendo EAD using the Wii Sports engine. The main new technology was the Wii Fit balance board, which took over 2 years to create and was inspired by sumo wrestler scales. Nintendo marketed Wii Fit through viral events and celebrity endorsements to showcase activities like hula hooping. Due to requiring the balance board, Wii Fit could only be purchased physically and sold over 90 copies per minute in its first week, becoming the 6th fastest selling console title. By December 2009, Wii Fit had sold over 22.5 million copies worldwide, making it the second best selling console game ever.