About 80% of wines are white and 15 vine varieties are authorized, of which Pinot Blanc, Chardonnay, and Pinot Noir are most successful. As in england, the proportion of sparkling wine has grown considerably, to nearly 40% by 2010. german crosses such as Kerner and Regent are also common as well as Auxerrois and Pinot Gris. Most vineyards are hardly more than 1 ha/2.5 acres and produce wine for local sale although quality has been increasing thanks partly to climate change. The wine industry of luxembourg to the south east is much bigger, more successful, and older, having been established in Roman times. Belgian viticulture has a long, if not continuous, history, however. In the era of charlemagne, vines were grown extensively in southern Belgium to provide wine for monks and were not abandoned until the 15th century, when a combination of climate change, military ravages, and the increasing influence of burgundy prejudiced the continuation of Belgian viticulture.