It's a curious thing. While we show you've been tracked since 2008, Twitter indicates that the account for @NACEorg was created in June of 2009.
My first guess would be that there used to be an account for @NACEorg before the current, for which we had data, but we forgot to update the record for the user when we started tracking the new account.
In any case, the first record we have for your account is on 15 March 2010. But, unfortunately, there is currently no way to view this data on the graph. You can get it from the .csv export that's part of your Premium package.