RSPB Big Garden Birdwatch - 2009

Now this year my results were: 4 Blackbirds; 1 Carrion Crow; 2 Chaffinches; 2 Coal Tits; 2 Great Tits; 5 Greenfinches; 2 Magpies; 1 Robin and 3 Woodpigeons.
Comparison: In 2008 - 1 Blackbird; 2 Blue Tits; 1 Coal Tit; 3 Great Tits; 2 Robins and 2 Woodpigeons
In 2007 - 1 Blackbird; 2 Blue Tits; 2 Coal Tits; 3 Great Tits; 2 Long-Tailed Tits; 1 Robin and 3 Woodpigeons.
I wonder where all these greenfinches have come from?