It utterly depends on the big picture with the airlines and what time you hit the market.
There are (very very occasionally) times, when it seems everyone who can correctly spell the word "airplane" can get a right hand seat with a big airline.
And there are also times (like right at the moment) when people with 5,000 hours of jet experience can't even get a look in at an air taxi operator.
The average in 'normal' times I guess, is around 1000 to 1500 hours, especially if you've got some multi time in there.