Winning percents from Baseballreference.com. The "National Association" of Professional Baseball Players (1871-1875)succeeded an earlier league of the similar name. Since many of the NA teams reformed into the National League in 1876, I count them here (even though MLB does not recognize the earlier NA as its founder). In 1903, historians tend to agree that the National League and the American League (begun in 1901) reached business peace and 1903 also is the first World Series between the NL and AL. The Index file begins with the NA in 1871. For all other leagues (including the AL, 1901-02), see MLB Rival Leagues.
The files are all in MSExcel format. So, use your "Save Target As" command to save them to your hard disk.
National Association (1871-75)/National League (1876-1902)/MLB (1903-present): 1871-2007