You all know the story. It is McGwire's 5th time on the ballot, each of the first 4 times he received about 23% of the vote. I can't see any reason that the numbers will change.
Mark's stats really don't have much to do with the vote but he hit 583 home runs and drove in 1414 (136 fewer than Fred McGriff) in a 16 year career with a .263/.394/.588 line. His career stats are here.
He was Rookie of the Year in 1987, was on 12 All-Star teams and won 1 Gold Glove (I have no idea how). His .588 SA is good for 8th all-time and the .982 OPS is 10th. He is also 10th in home runs. And, of course, he broke Roger Maris single season home run record in 1998 by hitting 70.
But then the numbers are just part of the story.