I added up the East vs. West records for as long as the NHL has had it properly divided (for example, no Pacific coast teams in the East). In all pairs I've put the West/Campbell on the top line and the East/Wales on the bottom line
2013-14
246-150-52
202-188-58
2013
Lockout year, no inter-conference play outside of the Blackhawks beating the Bruins 4-2
2011-12
136-93-41
134-99-37
2010-11
142-88-40
128-107-35
2009-10
155-87-28
115-118-37
2008-09
141-103-26
129-113-28
2007-08
83-53-14
67-67-16
2006-07
82-48-20
68-63-19
2005-06
79-52-19
71-62-17
2004-05
Lockout year
Overall record since the salary cap
W-L-OTL/SOL
1064-674-240
914-817-247
From here on I've lumped loser point games in with regular losses since there are no more shootouts
2003-04
W-L-T
119-118-33
118-119-33
2002-03
160-131-39
131-160-39
2001-02
168-132-30
132-168-30
2000-01
166-131-43
131-166-43
1999-00
168-122-46
122-168-46
At this point I couldn't get the records to balance out (one conference would have 130 wins while the other would only have 125 losses) so I went to average points per team.
1998-99
81.2
82.8
1997-98
82.3
81.7
1996-97
81.9
82.1
1995-96
80.8
83.2
1995
Lockout year, Devils sweep Red Wings
1993-94
82.9
84.9
1992-93
82.1
85.9
1991-92
78.3
81.7
1990-91
82.2
78.0
1989-90
81.0
79.1
1988-89
78.6
81.3
1987-88
74.9
84.6
1986-87
79.4
80.5
1985-86
73.1
86.3
1984-85
78.5
81.4
1983-84
76.3
83.3
1982-83
78.9
81.0
1981-82
80.3
79.7
Might be a few errors since I did it without double checking.
West wins 17 years, the East 13. 15 of the West's 17 wins have come since 97-98. If you are looking for what causes the switch, 1997-98 was the last year the Leafs were in the West. Toronto has been in the inferior conference for 25 of 30 seasons that NHL has divided the league by geography.