Mike Piazza’s election to the Baseball Hall of Fame has not ended questions about whether he used performance-enhancing drugs during his career. It was front and center Friday, when Piazza was made available on a conference call nine days before his induction in Cooperstown.

Piazza’s career statistics — a .308 batting average, 427 home runs and 1,335 RBIs — suggested first-ballot election, especially for a catcher, but it took four tries for him to receive the required percentage of votes.

Asked to comment on the speculation regarding his possible steroid use, Piazza, 47, credited Major League Baseball for instituting drug testing, saying, “I think there’s no question that the game has moved on and I think it’s better because of that and I’m just glad and honored that, you know, the writers have voted me into the Hall and it’s something I’m really much looking forward to and very, very excited about.”

Asked specifically if he used steroids, Piazza responded, “I’ve addressed that many times in the past . . . Thank you.”

Piazza played from 1992 to 2007. MLB began testing for banned substances in 2003.

In Piazza’s 2013 book “Long Shot,’’ he wrote, “Apparently, my career was a story that nobody cared to believe. Apparently, my success was the work of steroids. Had to be. Those were the rumors.” He wrote that he used androstenedione before it was banned by MLB and that he used amphetamines until MLB banned them in 2006.

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Former commissioner Fay Vincent, who held the job from 1989 to 1992, said he has reservations about Piazza entering the Hall. “Piazza’s the one that troubles me the most,’’ he said in a phone interview last week. “I have the great suspicion that he was using the drugs and yet he’s in the Hall of Fame. And he denies it. I have this neurotic worry that 10 years from now, he is going to write a book and disclose it all and what are we going to do? I mean, it’s very hard to reverse these decisions.’’

The Mets will retire Piazza’s No. 31 on July 30. He played for the Mets from 1998-2005. “The whole intensity of the New York market was a difficult transition for me,’’ he said, “but I knew that there was a reason I was there and I knew there was a reason I had to see it through and eventually was able to relax and start swinging the bat well, not pressing so much . . . I can honestly say the eight years that I was in New York, there wasn’t one day that when we lost the game, I wasn’t unhappy and I really wanted to prove my worth, prove to people that I was very serious about doing the best I can and . . . basically prove to them what I was worth and I wanted to perform for the fans and obviously win.’’