But it wasn't until the early twentieth century that women were allowed to ride astride. As a result, their exposure to horses throughout the most of human history would have been restricted. Horses were probably considered a'male thing' back then, when they were largely employed for labour and combat. Today, women account for about 15 percent of riders. That's about 50 million people worldwide. Of those, it is estimated that only one in ten rides astride. The rest still sit in front of them. The number of female riders is growing, however. In fact, it has grown by more than 20 percent since 2000. This leads some experts to believe that there will be as many as two billion people riding a horse sometime in the next few years. The majority of riders are in North America and Europe. About 85 percent of all riders live in these regions as well. The other 15 percent travel to places like Australia, New Zealand, South Africa, and Asia where they can be found working with horses as part of their local culture. There are several reasons why more women aren't riding. Money is often a factor. It can cost up to $100,000 to learn how to ride. Not every woman can afford to spend this kind of money on her hobby.