Traditionally, Vietnamese tea drinking is considered a hobby of the older, more learned members in households and in society in general, although currently it has been becoming more popular in younger demographics as well. Tea drinking would accompany aristocratic activities such as composing poems, tending flowers, or simply appreciating nature. Vietnamese people generally favor lighter teas with flower fragrance, such as green tea or floral-scented white tea. Vietnamese teas are produced in many areas that have been known for tea-house "retreats". For example, some are located amidst the immense tea forests of the Lamdong highlands, where there is a community of ancient Ruong houses built at the end of the 18th century. Vietnam has amongst the world's oldest trees, dating back to 1000 years. Green tea is the most popular amongst Vietnamese people. In 2011 it accounted for over 63% of overall retail volume sales. Vietnamese green teas have been largely unknown outside mainland Asia until the present day. Vietnamese green teas have a lower content of caffeine compared to Chinese green teas but higher caffeine levels than Japanese green teas. Recent free-enterprise initiatives are introducing these green teas to outside countries through new export activities. The Vietnam Tea Association (VITA) was founded on July 19, 1998, and their goal is to protect and inform growers, consumers, and business owners of Vietnamese teas. Of the different growing regions (mostly Northern and Central highlands), Thái Nguyên is considered to have the finest quality tea throughout Vietnam (and throughout Indochina by the French during colonization). Types Pure green tea is the standard tea in Vietnam. A high-grade Vietnamese green tea, especially from the Tân Cương commune of Thái Nguyên, has a strong bitter taste on the tip of the tongue, but later transforms to deep, lingering sweetness. Lotus tea (trà sen) is a specialty product of the Vietnamese tea industry. Generally, high-quality green tea leaves are placed within lotus flowers for a day to acquire the scent, then the tea leaves are removed and packaged. A higher grade of lotus tea is made with lotus petals mixed in with high-quality green tea leaves. Green tea style of Vietnam is to roll the leaves gently into crescents, and minimal handling. Vietnamese green teas are typically very potent. They are best brewed for most tastes for under 2 minutes using water temperature of 70 °C (160 °F). Beyond this time the tea will acquire