Using Australia data in the reference provided by MsSue,
20,743,300 (26 January 2007)
20,605,500 (26 January 2006)
20,171,300 (26 January 2005)
20,100,000 (26 January 2004)
19,438,000 (26 January 2003)
19,662,800 (26 January 2002)
19,436,000 (26 January 2001)
19,157,000 (26 January 2000)
The growth rate r from 2006 to 2007 was 0.67% per year. A longer-term average growth rate (r) from 2000 to 2007 (a six-year period)would be
20,743,300/19,157,000 = (1+r)^6
1.0828 = (1+r)^6
log 1.0828 = 6 log (1+r)
log(1+r) = 0.00576
1+r = 1.01335
r = 1.335%
These numbers agree well with yours. There does seem to have been a dropoff in the growth rate to 0.67% during the past year. You might want to use that rate for making your extrapolation (prediction) to 2008.