With specific regards to Oregon, the average retail cost of natural
gas per therm/CCF over the past ten years is as follows:

1997 $0.621
1998 $0.681
1999 $0.713
2000 $0.812
2001 $0.970
2002 $1.054
2003 $0.984
2004 $1.111
2005 $1.290
2006 $1.453

Source: http://tonto.eia.doe.gov/dnav/ng/hist/n3010or3A.htm

The average residential cost of electricity per kWh during this same
period is as follows:

1997 $0.0556
1998 $0.0582
1999 $0.0575
2000 $0.0588
2001 $0.0629
2002 $0.0712
2003 $0.0706
2004 $0.0718
2005 $0.0725
2006 $0.0748

Source: Table 8,
http://www.eia.doe.gov/cneaf/electri...es/oregon.html

Assuming an AFUE of 90 per cent and a HSPF of 8.5, the average cost
per kWh(e) of natural gas and electric heat in each of these years is
as follows (the third column represents the cost premium of natural
gas heat versus the aforementioned heat pump):

1997 $0.0235 $0.0222 1.1 X
1998 $0.0258 $0.0233 1.1 X
1999 $0.0270 $0.0230 1.2 X
2000 $0.0308 $0.0235 1.3 X
2001 $0.0368 $0.0252 1.5 X
2002 $0.0400 $0.0285 1.4 X
2003 $0.0373 $0.0282 1.3 X
2004 $0.0421 $0.0287 1.5 X
2005 $0.0489 $0.0290 1.7 X
2006 $0.0551 $0.0299 1.8 X

Please note these are state averages, so results will vary according
to the specific service provider.

Cheers,
Paul