New Zealand\'s service sector in the first six months saw its strongest half-year growth since 2007, according to the latest performance of services index (PSI) posted on Monday. The BNZ-Business New Zealand PSI for June was 55, making a year-to-date monthly average of 55.3 on a scale where above 50 indicates expansion and below 50 contraction. Business New Zealand chief executive Phil O\'Reilly said the PSI, like the performance of manufacturing index (PMI), was developing a trend of consistent and positive growth. \"The first six months of 2013 represent the best first half of the year since the survey began in 2007. Comments from respondents remain far more positive than negative, and focus on stronger activity, continuing growth and a sense of confidence back in the market,\" O\'Reilly said in a statement. All five main sub-indices were in expansion during June, led by new orders/business (59.7), followed by activity/sales (57.1), supplier deliveries (55), stock/inventories (53.8) and employment (50.1). The GDP-weighted BNZ-Business New Zealand performance of composite index, which combines the PMI and PSI, dropped 1.4 points from May to 55 for June.