The recent election of Yingluck Shinawatra (sister of former Thailand Prime Minister Thaksin Shinawatra) led me to go re-read the old NYTimes article on the 2006 coup that ousted him. Tucked away in that article is this little fun fact:
The military has a long history of political involvement, staging 18 coups since Thailand became a constitutional monarchy in 1932. The last one, in 1991, installed a military leader who was pushed from power by a popular uprising the next year.
Which is to say, between 1932 and 1991 Thailand averaged one military coup every 3.5 years.