I went big ...
Sample: All SPs with 120+ IP
Year: Correl (SO% Leader, Team, SO%)
1947: 0.33 (Ewell Blackwell, Reds, 17.8)
1948: 0.26 (Ewell Blackwell, Reds, 19.0)
1949: 0.33 (Curt Simmons, Phillies, 15.1)
1950: 0.12 (Ewell Blackwell, Reds, 17.1)
1951: 0.32 (Mickey McDermott, Red Sox, 17.4)
1952: 0.38 (Vinegar Bend Mizell, Cardinals, 17.5)
1953: 0.22 (Carl Erskine, Dodgers, 18.2)
1954: 0.30 (Billy Pierce, White Sox, 18.1)
1955: 0.32 (Herb Score, Indians, 25.1)
1956: 0.22 (Herb Score, Indians, 25.7)
1957: 0.20 (Bob Turley, Yankees, 21.0)
1958: 0.25 (Sam Jones, Cardinals, 21.6)
1959: 0.07 (Sandy Koufax, Dodgers, 25.5)
1960: 0.25 (Sandy Koufax, Dodgers, 26.2)
1961: 0.34 (Sandy Koufax, Dodgers, 25.2)
1962: 0.44 (Sandy Koufax, Dodgers, 29.0)
1963: 0.32 (Jim Maloney, Reds, 26.2)
1964: 0.40 (Sandy Koufax, Dodgers, 25.6)
1965: 0.48 (Sandy Koufax, Dodgers, 29.5)
1966: 0.44 (Sam McDowell, Indians, 27.9)
1967: 0.35 (Luis Tiant, Indians, 25.1)
1968: 0.47 (Luis Tiant, Indians, 26.8)
1969: 0.23 (Tom Griffin, Astros, 24.7)
1970: 0.30 (Ken Brett, Red Sox, 25.2)
1971: 0.41 (Tom Seaver, Mets, 26.2)
1972: 0.16 (Nolan Ryan, Angels, 28.5)
1973: 0.22 (Nolan Ryan, Angels, 28.3)
1974: 0.28 (Nolan Ryan, Angels, 26.5)
1975: 0.35 (Frank Tanana, Angels, 26.1)
1976: 0.21 (Nolan Ryan, Angels, 27.4)
1977: 0.55 (Nolan Ryan, Angels, 26.8)
1978: 0.30 (J.R. Richard, Astros, 26.6)
1979: 0.26 (J.R. Richard, Astros, 26.6)
1980: 0.29 (Steve Carlton, Phillies, 23.3)
1981: 0.30 (Fernando Valenzuela, Dodgers, 23.8)
1982: 0.47 (Mario Soto, Reds, 26.3)
1983: 0.37 (Steve Carlton, Phillies, 23.3)
1984: 0.26 (Dwight Gooden, Mets, 31.4)
1985: 0.35 (Sid Fernandez, Mets, 26.3)
1986: 0.36 (Mike Scott, Astros, 28.7)
1987: 0.37 (Nolan Ryan, Astros, 30.9)
1988: 0.42 (Roger Clemens, Red Sox, 27.4)
1989: 0.39 (Nolan Ryan, Rangers, 30.5)
1990: 0.32 (Nolan Ryan, Rangers, 28.4)
1991: 0.40 (Nolan Ryan, Rangers, 29.7)
1992: 0.40 (Randy Johnson, Mariners, 26.1)
1993: 0.54 (Randy Johnson, Mariners, 29.3)
1994: 0.33 (Randy Johnson, Mariners, 29.4)
1995: 0.37 (Randy Johnson, Mariners, 34)
1996: 0.48 (John Smoltz, Braves, 27.7)
1997: 0.53 (Randy Johnson, Mariners, 34.2)
1998: 0.52 (Kerry Wood, Cubs, 33.3)
1999: 0.55 (Pedro Martinez, Red Sox, 37.5)
2000: 0.54 (Pedro Martinez, Red Sox, 34.8)
2001: 0.48 (Randy Johnson, Diamondbacks, 36.7)
2002: 0.40 (Randy Johnson, Diamondbacks, 32.3)
2003: 0.57 (Kerry Wood, Cubs, 30.0)
2004: 0.52 (Randy Johnson, Diamondbacks, 30.1)
2005: 0.52 (Mark Prior, Cubs, 26.8)
2006: 0.50 (Scott Kazmir, Devil Rays, 26.7)
2007: 0.48 (Erik Bedard, Orioles, 30.2)
2008: 0.61 (Rich Harden, - - -, 30.4)
2009: 0.44 (Tim Lincecum, Giants, 28.8)
2010: 0.49 (Brandon Morrow, Blue Jays, 28.3)
2011: 0.48 (Brandon Beachy, Braves, 28.6)
2012: 0.35 (Stephen Strasburg, Nationals, 30.2)
2013: 0.54 (Yu Darvish, Rangers, 32.9)
2014: 0.48 (Clayton Kershaw, Dodgers, 31.9)
2015: 0.58 (Clayton Kershaw, Dodgers, 33.8)