In addition to the high school graduation "formal" that marks the end of Year 12, there is also an event that is sometimes held to celebrate completing the School Certificate at the end of Year 10 (or Year 11 in New Zealand), and always held after receiving Higher School Certificate at the end of Year 12 and includes a dinner and dance. The NSW Government announced the abolition of the School Certificate after 2011, with students in year 10 that year being the final cohort to sit the external examinations and receive the qualification. Subsequent Year 10 "Formals" have been deemed "unnecessary" due to the fact that the majority of Year 10 students now progress to Year 11. In previous years when 25–30% of students left high school in Year 10, the Formal was seen as a celebration for those departing, however, Year 10 Formals are still sometimes celebrated in the name of tradition. In year 11, students occasionally organize a "semi-formal" or "social" at the end of the school year, which is a more casual version of a formal. If a school has a sister school the social is typically organized in conjunction with them, as a "social event" for people to mingle and meet new people. The Valedictory Dinner (or Val as it is colloquially called) is an event that only occurs in Year 12. In New Zealand, most state school balls are held in the winter months, between June and August, while in Australia, a "formal" is held at the end of the year to mark the end of schooling, as is the Valedictory Dinner.