Actual season HRs appear in parentheses. Data is from 1876-2010. See first comment for team abbreviations. Press F11 if you can't see the whole quiz.
Home runs above average (HRAA) is a fun little stat I cooked up. For each season, a player's HRAA = HR - AB*LgHR/LgAB. When compared to the league average, home runs are "worth" less in high-HR eras, and more in low-HR eras. The quiz for career leaders is here: http://www.sporcle.com/games/DJC83/mlb-most-career-home-runs-above-average