Tourism has been a key factor in economic development for many Southeast Asian countries, especially Cambodia. According to UNESCO, "<answer>tourism</answer>, if correctly conceived, can be a tremendous development tool and an effective means of preserving the cultural diversity of our planet." Since the early 1990s, "even the non-ASEAN nations such as Cambodia, Laos, Vietnam and Burma, where the income derived from <answer>tourism</answer> is low, are attempting to expand their own <answer>tourism</answer> industries." In 1995, Singapore was the regional leader in <answer>tourism</answer> receipts relative to GDP at over 8%. By 1998, those receipts had dropped to less than 6% of GDP while Thailand and Lao PDR increased receipts to over 7%. Since 2000, Cambodia has surpassed all other ASEAN countries and generated almost 15% of its GDP from <answer>tourism</answer> in 2006.
From 2000, Cambodia has surpassed other ASEAN countries in generating GDP on which sector?
tourism