New South Wales leads the nation for investor activity in the residential property market but Queensland is catching up.According to the latest lending data from aggregator AFG, loans for property investors made up 45.9 per cent of all mortgages written by AFG brokers in NSW in June. This was down from 53.4 per cent in January.Mortgages arranged for property investors in Queensland rose from 33.5 per cent in January to 38.7 per cent in June. And in Victoria, investors accounted for 36.6 per cent of AFG's business in June.AFG's general manager of sales and operations, Mark Hewitt, said: "In NSW investors have accounted for more than two out of every five home loans each month for the past two and half years."The states with the highest levels of investor activity have the lowest first-home buyer participation. Of loans written by AFG brokers in June, the proportion of first-home buyers was 3.4 per cent in NSW, 5.6 per cent in Queensland, 11.3 per cent in Victoria, 12.9 per cent in South Australia and 23.1 per cent in Western Australia.AFG's average loan size in June was A$433,960.