I had a look at the police stats on burglary in WA and for the 2001 financial year, there were approx 3,300 burglaries per month with a clearance/solved rate of 14%. For the 2011 financial year ending, the number dropped to 2,200 per month but the clearance/solved rate also dropped to 11%. It would seem that, at first glance, the public has become more savvy about home security over time or are fed up and not reporting minor burglaries.
Looking at drug related statistics, they seem to have remained stable over the same periods, ie around 1350 offences per month with clearance/solved rate of approx 90%. However, what is not known is do these offences relate to the same types of drugs or have the types of drugs involved changed over time. It could be that offences relating to softer drugs may have dropped but that gap may have been taken up with harder drugs like crack etc and the side effect of these types of drugs may have a contributing effect on the brazeness of home invasions.....just a guess.
There are, no doubt, a number of factors that will have influenced the above. So one should be cautious with the above.
Fudd