The number of people who do yoga around the world has been growing steadily in the last 40 years. People in more than 180 countries will do the breathing and movement exercise on this year’s International Yoga Day. It is officially observed on June 21, the longest day of the year in the Northern Hemisphere. This year’s guiding idea is “peace.” The Daily Star newspaper, published in Bangladesh, reports that people in China have “yoga fever.” The report says the country will have the most people after India observing International Yoga Day. Public yoga events will be held in parks, vacation places and even at the Great Wall. The same report notes that in South Korea, sales of yoga mats and yoga towels have risen sharply this year.