Racingnsw have listed the number of starts trends for the last few years.
No surprise but the trend is still downward for Metro. In financial 2002/2003 season races averaged 10.7 runners per race, 2004/2005 was down to 9.5.
Looking at the class splits doesn't really highlight any particular area, though Fillies&Mares races have gone from 11.3 to 9.4(though there were 24 more races).
Provincial Racing has remained very solid with an average of 10.1 and with more races than Metro. Country had an increase to 9.8(with many fewer races). For trifecta punters looking for larger divi collects it's been better to punt interstate.
http://www.racingnsw.com.au/pdf/ra....sStatistics.pdf