Simply because the labour force number of 2007 as pictured above is only 500 persons stronger than the preceding year. The only two things that could explain such a small increment -- about 20 times less than the usual change -- would be an emigration of about 10,000 people in that particular year. I checked but didn't find anything. Or it could be the result of a kink in our population pyramid. Nothing there either.
And when you adjust the numbers you get a labour force that's about 20,000 larger in the last three years than the official statistics. That translates into an unemployment rate of 10.8% at the end of 2009 instead of the 7.7%.