1960 and 1980: Old school military colonel - generals. They thought they should show these puny civilians who the real boss was, hanged a few people including a prime minister, oppressed free speech and media.
1998 was different, it was a half coup, they disbanded government, created a huge vacuum of authority, caused the biggest economical depression in Turkish history, oppressed majority of people (Those pesky conservative people, why do they want to go to university?)
2016: They failed miserably regardless of their motivation. I hope this would be a lesson to them, Turks had enough of this crap.
https://en.wikipedia.org/wiki/1960_Turkish_coup_d'%C3%A9tat
https://en.wikipedia.org/wiki/1971_Turkish_military_memorand...
https://en.wikipedia.org/wiki/1980_Turkish_coup_d'%C3%A9tat
https://en.wikipedia.org/wiki/1997_Turkish_military_memorand...