A sedentary lifestyle plays a significant role in obesity.  Worldwide there has been a large shift towards less physically demanding work,    and currently at least 30% of the world's population gets insufficient exercise.  This is primarily due to increasing use of mechanized transportation and a greater prevalence of labor-saving technology in the home.    In children, there appear to be declines in levels of physical activity due to less walking and physical education.  World trends in active leisure time physical activity are less clear. The World Health Organization indicates people worldwide are taking up less active recreational pursuits, while a study from Finland  found an increase and a study from the United States found leisure-time physical activity has not changed significantly.  A 2011 review of physical activity in children found that it may not be a significant contributor.