<human>:  When did the Greek debt crisis start?
<bot>: The Greek debt crisis began in 2009, when the Greek government was unable to pay back its debts. This led to the country’s inability to pay back its debts to private investors. In 2010, Greece entered a bailout program, which included austerity measures and the imposition of capital controls. In 2012, Greece defaulted on its debts to private investors.