Tiger: It's getting harder to win majors

(CNN) -- It's four years since Tiger Woods last won a major title, and the 14-time champion admits it's much harder now than when he was in his prime.

There have been 16 different winners in the past 16 majors, and there's nothing to suggest that trend will be broken at this week's PGA Championship at Kiawah Island in South Carolina.

Woods, who has climbed back to No. 2 in the rankings, won the season's closing major for the fourth time in 2007 but has been stuck on 14 overall since his U.S. Open victory the following year.

The American has won three times on the 2012 PGA Tour to go second on the all-time list, but his tie for third at last month's British Open was his best finish in the first three of golf's four prestige events.

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"Golf is getting deep. There's so many guys with a chance to win," he told reporters on Tuesday.

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"The margin is getting smaller. There may be 16 different winners, but you look at the cuts -- the cuts are getting lower. The scores between the leader and the guy who is 70th and tied, sometimes it's 10 shots or less, which is amazing."

Woods has a strong record at the PGA, with eight top-10 finishes in 14 appearances, but last year he missed the cut as Keegan Bradley became yet another first-time major winner.

Bradley, who won last weekend's WGC-Bridgestone Invitational as Woods tied for eighth, has been followed by this year's Masters winner Bubba Watson and U.S. Open champion Webb Simpson.

Veteran Ernie Els broke that first-time trend at Royal Lytham last month when he denied Adam Scott his maiden major -- the South African claimed his first since 2002 and fourth overall.

"The margins are so small, and if you've got margins that are that small you're going to get guys who win once here and there," Woods said.

"If you just make the cut nowadays you're within nine shots of the lead sometimes. That's easily doable on a weekend. And it's just amazing -- you've got 70-plus guys within 10 shots it seems like at every Tour event.

"That wasn't always the case. It used to be 14, 15 shots sometimes, but it's just so much smaller now, the margins."

Woods is still four short of Jack Nicklaus' record 18 major crowns, but the 36-year-old insists that he still has plenty of time to catch the "Golden Bear."

"Well, I figure it's going to take a career. It's going to take a long time," he said. "Jack didn't finish his until he was 46, so if you go by that timetable, I've got 10 more years.

"Four more majors is a lot. I've got plenty of time. With the training regimes that we have now and seeing guys play well, you can get on the right golf course and contend.

"So we can play late in our careers just because of our training, and also just getting the right golf course. You know, who knows."