1. Advances in travel technology: now there is a more available and wider range of ways to travel, whether in using cars, buses or planes; plus the fare has become more affordable or budget-friendly.
People have more money to spend on travel because most families now have 2 income earners but with less children and are car-owners. 
3. Various forms of media offer a wider coverage of holiday types which tend to increase the demand for travel.  More people become exposed to travel packages through the newspapers, TV and the internet .