Police carried out 2839 controlled purchase operations in 2012 and caught 258 premises selling alcohol to minors. In 2013 they carried out 2771 and caught 232. In 2014 they carried out 3013 and caught 224.
Mr Buttar said police were always striving for a decrease in the supply of alcohol to minors.
"Our ideal situation around these controlled purchase operations would be that there were no sales to minors at all," he said.
One Northland police sergeant believes liquor vendors are getting the message about the risks of selling alcohol to minors.
Police figures showed four Northland premises were caught selling alcohol to minors in operations in the area last year compared to 12 in 2013.
The reduced level of breaches were discovered despite more stings. In 2013, 100 controlled purchase operations were carried out while there were 111 in 2014.
Whangarei/Kaipara area prevention manager Senior Sergeant John Fagan said the hospitality industry was more aware of their obligations and the risks around selling alcohol to minors, especially since the introduction of the full Sale and Supply of Alcohol Act 2012 in December 2013.
Better co-ordination in the vetting of new licensees and managers had also contributed to the drop in sales to minors, he said.
No Wanganui premises were caught selling alcohol to minors in Wanganui or Marton last year following a significant reduction in the number of controlled purchase operations in the area. In 2013, two were caught in Wanganui and another two in Marton.
Police carried out more than three times as many operations across the two areas in 2013 as in 2014, at 96 compared to 28.
Wanganui police alcohol harm reduction officer, Constable Keith Thomson said it wasn't unusual for the number of controlled purchase operations to differ from year to year.
Alongside controlled purchase operations police used a number of tools and initiatives including foot patrols, licensed premise checks, and working with local community groups, councils, businesses, and agencies to prevent alcohol harm.
Wanganui District Councillor Philippa Baker-Hogan said she was surprised at such a significant drop in the number of controlled purchase operations in the area between 2013 and 2014.
"I haven't received anything to tell me that we should take our finger off the pulse on this issue. It just seems a significant reduction."
Ms Baker-Hogan, who is also on the Whanganui District Health Board, said the purchase and use of alcohol was an issue in the area. However, she agreed controlled purchase operations were just one tool in a broader tool kit for addressing youth drinking.