It depends on what you mean by 'single'...

If we define it as not being in a committed relationship since the time one started becoming romantically involved with others, then for me it would be the last 6 years. I am 28 years old, and have had two serious relationships (2 years, and then another one for around 1 year). But I have had a ton of dates, casual partners, etc... but let me tell you that I don't do that stuff like I used to because I am looking for the real thing the last couple of years, and it totally sucks how lonely I really am.