BANGKOK, Dec 30 (Reuters) - Thailand"s household debt to gross domestic product ratio stood at 89.3% in the third quarter, unchanged from the previous quarter, central bank data showed on Thursday. However, the amount of household debt was 14.35 trillion baht ($430.16 billion) at the end of September, up from 14.28 trillion at the end of June, or equal to 89.3% of GDP, already among Asia"s highest. The Bank of Thailand started compiling household debt data in 2003. ($1 = 33.3600 baht)