How many baseball teams won back to back series?

Here's a list of repeat World Series champions through 2009:

1. Chicago Cubs, 1907-08

2. Philadelphia Athletics, 1910-11

3. Boston Red Sox, 1915-16

4. New York Giants, 1921-22

5. New York Yankees, 1927-28

6. Philadelphia Athletics, 1929-30

7. New York Yankees, 1936-39 (won four in a row)

8. New York Yankees, 1949-53 (won five in a row)

9. New York Yankees, 1961-62

10. Oakland A's, 1972-74 (won three in a row)

11. Cincinnati Reds, 1975-76

12. New York Yankees, 1977-78

13. Toronto Blue Jays 1992-93

14. New York Yankees 1998-2000 (three in a row)